Antiasthmatic Compounds Targeting ß2-Adrenergic Receptor from Perilla frutescens Improved Lung Inflammation by Inhibiting the NF-κB Signaling Pathway.

Asthma is a highly prevalent and heterogeneous chronic respiratory disease and is often treated with inhaled corticosteroids or in combination with a ß2-adrenergic receptor (ß2-AR) agonist. However, around 5% of asthma remains uncontrolled, and more effective antiasthmatic drugs with known mechanisms are in high demand. Herein, we immobilized ß2-AR on the polystyrene amino microsphere surface in a one-step fashion. The successful immobilization of ß2-AR was verified by scanning electron microscopy and chromatographic analysis. We screened rosmarinic acid (RA) as the bioactive compound targeting ß2-AR in Perilla frutescens (L.) Britton by mass spectroscopy. The binding constant between RA and ß2-AR was determined to be 2.95 × 104 M-1 by adsorption energy distribution and frontal analysis. The antiasthmatic effect and mechanism of RA were examined on a murine model of allergic asthma induced by ovalbumin (OVA) and aluminum hydroxide. The results showed that RA significantly reduced lung inflammatory cell numbers, the production of Th2 cytokines, and the secretion of total IgE, OVA-specific IgE, and eotaxin. The decreased inflammatory cell infiltration and mucus hypersecretion were associated with the inhibition of the NF-κB signaling pathway. Moreover, the mRNA expression levels of AMCase, CCL11, CCR3, Ym2, and E-selectin in the lung tissues were effectively reduced. It is the first time that RA was proven to target ß2-AR and be effective in counteracting allergic airway inflammation via the NF-κB signaling pathway. Therefore, the immobilized ß2-AR preserves the potential in screening antiasthmatic compounds from herbal medicine, and RA can be developed as an effective agent for the treatment of allergic asthma.

Short Communication: Beta-adrenergic agonists alter oxidative phosphorylation in primary myoblasts.

Beta-adrenergic agonists (ß-AAs) are widely used supplements in beef and pork production to improve feed efficiency and increase lean muscle mass, yet little is known about the molecular mechanism by which ß-AAs achieve this outcome. Our objective was to identify the influence of ractopamine HCl and zilpaterol HCl on mitochondrial respiratory activity in muscle satellite cells isolated from crossbred beef steers (N = 5), crossbred barrows (N = 2), Yorkshire-cross gilts (N = 3), and commercial weather lambs (N = 5). Real-time measurements of oxygen consumption rates (OCRs) were recorded using extracellular flux analyses with a Seahorse XFe24 analyzer. After basal OCR measurements were recorded, zilpaterol HCl, ractopamine HCl, or no ß-AA was injected into the assay plate in three technical replicates for each cell isolate. Then, oligomycin, carbonyl cyanide-p-trifluoromethoxyphenylhydrazone, and rotenone were injected into the assay plate sequentially, each inducing a different cellular state. This allowed for the measurement of OCR at these states and for the calculation of the following measures of mitochondrial function: basal respiration, non-mitochondrial respiration, maximal respiration, proton leak, adenosine triphosphate (ATP)-linked respiration, and spare respiratory capacity. Incubation of bovine cells with either zilpaterol HCl or ractopamine HCl increased maximal respiration (P = 0.046) and spare respiratory capacity (P = 0.035) compared with non-supplemented counterparts. No difference (P > 0.05) was observed between zilpaterol HCl and ractopamine HCl for maximal respiration and spare respiratory capacity in bovine cell isolates. No measures of mitochondrial function (basal respiration, non-mitochondrial respiration, maximal respiration, proton leak, ATP-linked respiration, and spare respiratory capacity) were altered by ß-AA treatment in ovine or porcine cells. These findings indicate that ß-AAs in cattle may improve the efficiency of oxidative metabolism in muscle satellite cells by modifying mitochondrial respiratory activity. The lack of response by ovine and porcine cells to ß-AA incubation also demonstrates differing physiological responses to ß-AA across species, which helps to explain the variation in its effectiveness as a growth supplement.

Beta-adrenergic agonists (ß-AAs) are supplemented to pigs and cattle to improve growth performance, carcass weight, and loin muscle area. Little is known about the mechanism taking place within individual cells by which ß-AAs achieve this outcome. Previous work reported that ß-AA supplementation improves the efficiency in which cells use glucose as an energy source and alters the expression of genes related to mitochondrial function, a key component of cellular energy production. To further our understanding of the impact of ß-AA supplementation on these cellular functions, our objective was to identify the influence of two ß-AAs used in livestock production, ractopamine HCl and zilpaterol HCl, on the mitochondrial respiratory activity of cells collected from the loin muscle and grown in culture. We isolated cells from cattle, pig, and sheep muscle and measured the oxygen consumption of the cells after treatment with ractopamine HCl, zilpaterol HCl, or with no supplement. We found that both ractopamine HCl and zilpaterol HCl enhance the efficiency of cellular energy production during a state of cellular stress in bovine muscle cells. There was no appreciable effect of the supplement on the energy production of pig or sheep cells. These data indicate that ß-AA supplementation in cattle may increase the muscle cell energy production capacity compared with non-supplemented cells. This study also demonstrates that the efficiency of cell energy production is one plausible mechanism underlying species differences in the response to ß-AA supplementation.

Global Quality Statements on Reliever Use in Asthma in Adults and Children Older than 5 Years of Age.

INTRODUCTION: Widespread misuse of short-acting beta-agonists (SABAs) may contribute to asthma-related morbidity and mortality. Recognizing this, the Global Initiative for Asthma neither recommends SABA monotherapy nor regards this formulation as a preferred reliever. Many health systems and healthcare professionals (HCPs) experience practical issues in implementing guidelines. Clear quality standards can drive improvements in asthma care and encourage implementation of global and national medical guidelines. METHODS: A steering group of global asthma experts came together between May and September 2019 to develop quality statements codifying the minimum elements of good quality asthma care. These statements were either evidence based (when robust evidence was available) or reflected a consensus based on clinical expertise and experience of the group. RESULTS: The quality statements (and associated essential criteria) developed emphasize key elements concerning (1) objective diagnosis specific to individual symptoms, (2) treatment appropriate to the long-term management of asthma as an inflammatory disease, consistent with evidence-based recommendations, (3) controlled dispensing of SABA canisters and monitoring to prevent overuse, (4) regular review of patients after treatment initiation or change, and (5) follow-up of patients in primary care after treatment for an exacerbation in a hospital or an emergency department. CONCLUSIONS: The steering group proposes quality statements that national and local clinical groups can implement as quantitative quality standards that are appropriate to their local circumstances, including during the coronavirus disease 2019 (Covid-19) pandemic. By translating these statements into locally relevant quality standards, primary care physicians and HCPs can encourage optimal management and reduce preventable healthcare interactions. The evidence-based evolution of care encapsulated in these statements will further engender high-quality, patient-centered holistic management that addresses asthma as an inflammatory disease. In particular, the statements empower self-management by patients and encourage health-promoting behaviors, which are essential to reduce exacerbations, the primary goal of asthma management.

Relationship between beta-adrenergic agonists, calpain system activity and beef texture: A systematic review.

The objective was to conduct a systematic review to evaluate the effects of dietary supplementation with beta-adrenergic agonists on calpains and calpastatin activity in bovine muscle and changes in meat tenderness. A survey was conducted in June 2019 on Science Direct, Web of Science, Scopus, PubMed and Capes Periodicals, using four keyword combinations: agonist and calpain and cattle; agonist and calpain and bovine; agonist and calpain and heifers; agonist and calpain and steers. Thirteen studies were selected, 54% concluded that supplementation with beta-adrenergic agonists increases calpastatin activity, 23% observed increase in their gene expression and 23% reported no effect on activity or expression of this enzyme. Nine studies evaluated the influence of beta-adrenergic agonists supplementation on meat texture and all found an increase in shear force values. There is strong evidence that beta-adrenergic agonists may increase calpastatin activity in the muscle, causing damage to meat tenderness.

Sex-differences in cholinergic, nicotinic, and ß-adrenergic cutaneous vasodilation: Roles of nitric oxide synthase, cyclooxygenase, and K+ channels.

Previous studies indicate that sex-related differences exist in the regulation of cutaneous vasodilation, however, the mechanisms remain unresolved. We assessed if sex-differences in young adults exist for cholinergic, nicotinic, and ß-adrenergic cutaneous vasodilation with a focus on nitric oxide synthase (NOS), cyclooxygenase (COX), and K+ channel mechanisms. In twelve young men and thirteen young women, four intradermal forearm skin sites were perfused with the following: 1) lactated Ringer's solution (control), 2) 10 mM Nω-nitro-l-arginine, a non-selective NOS inhibitor, 3) 10 mM ketorolac, a non-selective COX inhibitor, or 4) 50 mM BaCl2, a nonspecific K+ channel blocker. At all four sites, cutaneous vasodilation was induced by 1) 10 mM nicotine, a nicotinic receptor agonist, 2) 100 µM isoproterenol, a nonselective ß-adrenergic receptor agonist, and 3) 2 mM and 2000 mM acetylcholine, an acetylcholine receptor agonist. Nicotine and isoproterenol were administered for 3 min, whereas each acetylcholine dose was administered for 25 min. Regardless of treatment site, cutaneous vasodilation in response to nicotine and a high dose of acetylcholine (2000 mM) were lower in women than men. By contrast, isoproterenol induced cutaneous vasodilation was greater in women vs. men. Irrespective of sex, NOS inhibition or K+ channel blockade attenuated isoproterenol-mediated cutaneous vasodilation, whereas K+ channel blockade decreased nicotine-induced cutaneous vasodilation. Taken together, our findings indicate that while the mechanisms underlying cutaneous vasodilation are comparable between young men and women, sex-related differences in the magnitude of cutaneous vasodilation do exist and this response differs as a function of the receptor agonist.

Heat stress-induced deficits in growth, metabolic efficiency, and cardiovascular function coincided with chronic systemic inflammation and hypercatecholaminemia in ractopamine-supplemented feedlot lambs.

Heat stress hinders growth and well-being in livestock, an effect that is perhaps exacerbated by the ß1 agonist ractopamine. Heat stress deficits are mediated in part by reduced feed intake, but other mechanisms involved are less understood. Our objective was to determine the direct impact of heat stress on growth and well-being in ractopamine-supplemented feedlot lambs. Commercial wethers were fed under heat stress (40 °C) for 30 d, and controls (18 °C) were pair-fed. In a 2 × 2 factorial, lambs were also given a daily gavage of 0 or 60 mg ractopamine. Growth, metabolic, cardiovascular, and stress indicators were assessed throughout the study. At necropsy, 9th to 12th rib sections (four-rib), internal organs, and feet were assessed, and sartorius muscles were collected for ex vivo glucose metabolic studies. Heat stress increased (P < 0.05) rectal temperatures and respiration rates throughout the study and reduced (P < 0.05) weight gain and feed efficiency over the first week, ultrasonic loin-eye area and loin depth near the end of the study, and four-rib weight at necropsy. Fat content of the four-rib and loin were also reduced (P < 0.05) by heat stress. Ractopamine increased (P < 0.05) loin weight and fat content and partially moderated the impact of heat stress on rectal temperature and four-rib weight. Heat stress reduced (P < 0.05) spleen weight, increased (P < 0.05) adrenal and lung weights, and was associated with hoof wall overgrowth but not organ lesions. Ractopamine did not affect any measured indicators of well-being. Heat stress reduced (P < 0.05) blood urea nitrogen and increased (P < 0.05) circulating monocytes, granulocytes, and total white blood cells as well as epinephrine, TNFα, cholesterol, and triglycerides. Cortisol and insulin were not affected. Heat stress reduced (P < 0.05) blood pressure and heart rates in all lambs and increased (P < 0.05) left ventricular wall thickness in unsupplemented but not ractopamine-supplemented lambs. No cardiac arrhythmias were observed. Muscle glucose uptake did not differ among groups, but insulin-stimulated glucose oxidation was reduced (P < 0.05) in muscle from heat-stressed lambs. These findings demonstrate that heat stress impairs growth, metabolism, and well-being even when the impact of feed intake is eliminated by pair-feeding and that systemic inflammation and hypercatecholaminemia likely contribute to these deficits. Moreover, ractopamine improved muscle growth indicators without worsening the effects of heat stress.

Cardiac power output accurately reflects external cardiac work over a wide range of inotropic states in pigs.

BACKGROUND: Cardiac power output (CPO), derived from the product of cardiac output and mean aortic pressure, is an important yet underexploited parameter for hemodynamic monitoring of critically ill patients in the intensive-care unit (ICU). The conductance catheter-derived pressure-volume loop area reflects left ventricular stroke work (LV SW). Dividing LV SW by time, a measure of LV SW min- 1 is obtained sharing the same unit as CPO (W). We aimed to validate CPO as a marker of LV SW min- 1 under various inotropic states. METHODS: We retrospectively analysed data obtained from experimental studies of the hemodynamic impact of mild hypothermia and hyperthermia on acute heart failure. Fifty-nine anaesthetized and mechanically ventilated closed-chest Landrace pigs (68 ± 1 kg) were instrumented with Swan-Ganz and LV pressure-volume catheters. Data were obtained at body temperatures of 33.0 °C, 38.0 °C and 40.5 °C; before and after: resuscitation, myocardial infarction, endotoxemia, sevoflurane-induced myocardial depression and beta-adrenergic stimulation. We plotted LVSW min- 1 against CPO by linear regression analysis, as well as against the following classical indices of LV function and work: LV ejection fraction (LV EF), rate-pressure product (RPP), triple product (TP), LV maximum pressure (LVPmax) and maximal rate of rise of LVP (LV dP/dtmax). RESULTS: CPO showed the best correlation with LV SW min- 1 (r2 = 0.89; p < 0.05) while LV EF did not correlate at all (r2 = 0.01; p = 0.259). Further parameters correlated moderately with LV SW min- 1 (LVPmax r2 = 0.47, RPP r2 = 0.67; and TP r2 = 0.54). LV dP/dtmax correlated worst with LV SW min- 1 (r2 = 0.28). CONCLUSION: CPO reflects external cardiac work over a wide range of inotropic states. These data further support the use of CPO to monitor inotropic interventions in the ICU.

Cardiorespiratory noise correction improves the ASL signal.

Cardiorespiratory fluctuations such as changes in heart rate or respiration volume influence the temporal dynamics of cerebral blood flow (CBF) measurements during arterial spin labeling (ASL) fMRI. This "physiological noise" can confound estimates of resting state network activity, and it may lower the signal-to-noise ratio of ASL during task-related experiments. In this study we examined several methods for minimizing the contributions of both synchronized and non-synchronized physiological noise in ASL measures of CBF, by combining the RETROICOR approach with different linear deconvolution models. We evaluated the amount of variance in CBF that could be explained by each method during physiological rest, in both resting state and task performance conditions. To further demonstrate the feasibility of this approach, we induced low-frequency cardiorespiratory deviations via peripheral adrenergic stimulation with isoproterenol, and determined how these fluctuations influenced CBF, before and after applying noise correction. By suppressing physiological noise, we observed substantial improvements in the signal-to-noise ratio at the individual and group activation levels. Our results suggest that variations in cardiac and respiratory parameters can account for a large proportion of the variance in resting and task-based CBF, and indicate that regressing out these non-neuronal signal variations improves the intrinsically low signal-to-noise ratio of ASL. This approach may help to better identify and control physiologically driven activations in ASL resting state and task-based analyses.

Restricting glycolysis impairs brown adipocyte glucose and oxygen consumption.

During thermogenic activation, brown adipocytes take up large amounts of glucose. In addition, cold stimulation leads to an upregulation of glycolytic enzymes. Here we have investigated the importance of glycolysis for brown adipocyte glucose consumption and thermogenesis. Using siRNA-mediated knockdown in mature adipocytes, we explored the effect of glucose transporters and glycolytic enzymes on brown adipocyte functions such as consumption of glucose and oxygen. Basal oxygen consumption in brown adipocytes was equally dependent on glucose and fatty acid oxidation, whereas isoproterenol (ISO)-stimulated respiration was fueled mainly by fatty acids, with a significant contribution from glucose oxidation. Knockdown of glucose transporters in brown adipocytes not only impaired ISO-stimulated glycolytic flux but also oxygen consumption. Diminishing glycolytic flux by knockdown of the first and final enzyme of glycolysis, i.e., hexokinase 2 (HK2) and pyruvate kinase M (PKM), respectively, decreased glucose uptake and ISO-stimulated oxygen consumption. HK2 knockdown had a more severe effect, which, in contrast to PKM knockdown, could not be rescued by supplementation with pyruvate. Hence, brown adipocytes rely on glucose consumption and glycolytic flux to achieve maximum thermogenic output, with glycolysis likely supporting thermogenesis not only by pyruvate formation but also by supplying intermediates for efferent metabolic pathways.

Effect of ovariectomy on intracellular Ca2+ regulation in guinea pig cardiomyocytes.

This study addressed the hypothesis that long-term deficiency of ovarian hormones after ovariectomy (OVx) alters cellular Ca2+-handling mechanisms in the heart, resulting in the formation of a proarrhythmic substrate. It also tested whether estrogen supplementation to OVx animals reverses any alterations to cardiac Ca2+ handling and rescues proarrhythmic behavior. OVx or sham operations were performed on female guinea pigs using appropriate anesthetic and analgesic regimes. Pellets containing 17ß-estradiol (1 mg, 60-day release) were placed subcutaneously in selected OVx animals (OVx + E). Cardiac myocytes were enzymatically isolated, and electrophysiological measurements were conducted with a switch-clamp system. In fluo-4-loaded cells, Ca2+ transients were 20% larger, and fractional sarcoplasmic reticulum (SR) Ca2+ release was 7% greater in the OVx group compared with the sham group. Peak L-type Ca2+ current was 16% larger in OVx myocytes with channel inactivation shifting to more positive membrane potentials, creating a larger "window" current. SR Ca2+ stores were 22% greater in the OVx group, and these cells showed a higher frequency of Ca2+ sparks and waves and shorter wave-free intervals. OVx myocytes showed higher frequencies of early afterdepolarizations, and a greater percentage of these cells showed delayed afterdepolarizations after exposure to isoprenaline compared with sham myocytes. The altered Ca2+ regulation occurring in the OVx group was not observed in the OVx + E group. These findings suggest that long-term deprivation of ovarian hormones in guinea pigs lead to changes in myocyte Ca2+-handling mechanisms that are considered proarrhythmogenic. 17ß-Estradiol replacement prevented these adverse effects.NEW & NOTEWORTHY Ovariectomized guinea pig cardiomyocytes have higher frequencies of Ca2+ waves, and isoprenaline-challenged cells display more early afterdepolarizations, delayed afterdepolarizations, and extra beats compared with sham myocytes. These alterations to Ca2+ regulation were not observed in myocytes from ovariectomized guinea pigs supplemented with 17ß-estradiol, suggesting that ovarian hormone deficiency modifies cardiac Ca2+ regulation, potentially creating proarrhythmic substrates.

Evaluation of Commercial ß-Agonists, Dietary Protein, and Shade on Fecal Shedding of Escherichia coli O157:H7 from Feedlot Cattle.

Escherichia coli O157:H7 is a foodborne pathogen commonly associated with cattle feces. Diet, including dietary supplements such as ß-agonists, may impact fecal shedding of this pathogen. A series of three experiments were conducted to determine if the ß-agonists ractopamine hydrochloride (RAC) or zilpaterol hydrochloride (ZH) would impact the level or prevalence of fecal E. coli O157:H7 shedding. In Experiment 1, dietary RAC did not impact fecal shedding of E. coli O157:H7 based on the level or prevalence, but the addition of dietary soybean meal (SBM) in the study did reduce E. coli O157:H7 shedding. In Experiments 2 and 3, dietary ZH did not affect fecal E. coli O157:H7 shedding as determined by enumeration or prevalence, but in Experiment 2 the addition of 30% (dry matter basis) wet distillers grains with solubles (WDGS) in the diet tended to increase E. coli O157:H7 shedding. Shade is a potential management tool to reduce heat stress in cattle, and in Experiment 3 the presence of shade over the feedlot pens did not affect E. coli O157:H7 shedding. The use of ß-agonists in cattle diets did not significantly affect fecal shedding of E. coli O157:H7, and in particular the percentage of animals shedding enumerable levels of the pathogen did not change, indicating that there was not a change in colonization. As has been reported previously and indicated again in this study, the use of WDGS in the diet may increase E. coli O157:H7 shedding. In contrast, the addition of SBM to cattle diets, to increase the dietary crude protein, appeared to reduce E. coli O157:H7 shedding, but this potential dietary intervention needs to be confirmed with additional research.

Antispasmodic and bronchorelaxant activities of Salsola imbricata are mediated through dual Ca+2 antagonistic and ß-adrenergic agonistic effects.

CONTEXT: Salsola imbricata Forssk. (Chenopodiaceae) has folkloric repute for the treatment of various gastrointestinal and respiratory ailments. OBJECTIVE: The present study investigates spasmolytic and bronchorelaxant effects of S. imbricata. MATERIALS AND METHODS: The crude aqueous-ethanol extract of the aerial parts of S. imbricata and its fractions, in cumulative concentrations (0.01-10 mg/mL), were tested on contractions of isolated rabbit jejunum and tracheal preparations. Furthermore, concentration response curves (CRCs) of Ca+2 and carbachol were constructed in the absence and presence of the extract. Standard organ bath methods were used. RESULTS: The crude extract relaxed spontaneous, K+ (80 mM) and carbachol (1 µM)-induced contractions in jejunum preparations with respective EC50 values of 0.40 (0.35-0.46), 0.69 (0.60-0.79) and 0.66 (0.57-0.75) mg/mL. It shifted Ca+2 CRCs rightward in nonparallel manner. In isolated tracheal preparations, the crude extract caused relaxation of K+ (80 mM) and carbachol (1 µM)-induced contractions with EC50 values of 0.86 (0.75-0.98) and 0.74 (0.66-0.84) mg/mL, respectively. It displaced carbachol CRCs rightward with suppression of maximal response. In both tissues, pretreatment with propranolol (1 µM) caused rightward shift in inhibitory CRCs of the extract against carbachol-induced contractions. The ethyl acetate fraction was found more potent in relaxing smooth muscle contractions than the parent extract and its aqueous fraction. DISCUSSION AND CONCLUSION: The results suggest that the spasmolytic and bronchorelaxant activities of S. imbricata are related to Ca+2 antagonistic and ß-adrenergic agonistic effects, thus justifying some of the traditional uses of the plant.

The effects of animal age, feeding regime and a dietary beta-agonist on tenderness of three beef muscles.

BACKGROUND: Animal age as determined by number of permanent incisors (p. i.) is used in classification of beef carcasses to describe expected meat tenderness. However, animals differing in age are reared under different production systems (pasture or feedlot). In addition to age, other factors associated with particular production systems may also influence the palatability of meat. Therefore, the effects of age combined with feeding regime and the supplementation of a beta-agonist (zilpaterol) on the tenderness of M. longissimus lumborum (LL), M. semitendinosus (ST) and M. biceps femoris (BF) muscles were investigated. RESULTS: Tenderness of LL cuts was least affected by age but zilpaterol significantly decreased tenderness and ageing potential. Tenderness of high-collagen cuts (BF and ST) was negatively affected by age due to reduced collagen solubility. The effect of zilpaterol on these cuts was less significant and BF and ST cuts of the grain-fed A-age animals (0 p. i.) supplemented with zilpaterol (AZ) were more tender than the same cuts of grass-fed animals with 1-2 p. i. (AB-age) and grass-fed animals with 3-6 p. i. (B-age) according to Warner-Bratzler shear force (WBSF) and sensory analysis for tenderness. CONCLUSION: This study indicates that beta-agonists may influence variation in tenderness within an age class more than age or feeding regime. © 2016 Society of Chemical Industry.

Nitric oxide synthase and cyclooxygenase modulate ß-adrenergic cutaneous vasodilatation and sweating in young men.

KEY POINTS: ß-Adrenergic receptor agonists such as isoproterenol induce cutaneous vasodilatation and sweating in humans, but the mechanisms underpinning this response remain unresolved. Using intradermal microdialysis, we evaluated the roles of nitric oxide synthase (NOS) and cyclooxygenase (COX) in ß-adrenergic cutaneous vasodilatation and sweating elicited by administration of isoproterenol. We show that while NOS contributes to ß-adrenergic cutaneous vasodilatation, COX restricts cutaneous vasodilatation. We also show that combined inhibition of NOS and COX augments ß-adrenergic sweating These new findings advance our basic knowledge regarding the physiological control of cutaneous blood flow and sweating, and provide important and new information to better understand the physiological significance of ß-adrenergic receptors in the skin. ABSTRACT: ß-Adrenergic receptor agonists such as isoproterenol can induce cutaneous vasodilatation and sweating in humans, but the mechanisms underpinning this response remain unresolved. We evaluated the hypotheses that (1) nitric oxide synthase (NOS) contributes to ß-adrenergic cutaneous vasodilatation, whereas cyclooxygenase (COX) limits the vasodilatation, and (2) COX contributes to ß-adrenergic sweating. In 10 young males (25 ± 5 years), cutaneous vascular conductance (CVC) and sweat rate were evaluated at four intradermal forearm skin sites infused with (1) lactated Ringer solution (control), (2) 10 mm Nω -nitro-l-arginine (l-NNA), a non-specific NOS inhibitor, (3) 10 mm ketorolac, a non-specific COX inhibitor, or (4) a combination of l-NNA and ketorolac. All sites were co-administered with a high dose of isoproterenol (100 µm) for 3 min to maximally induce ß-adrenergic sweating (ß-adrenergic sweating is significantly blunted by subsequent activations). Approximately 60 min after the washout period, three incremental doses of isoproterenol were co-administered (1, 10 and 100 µm each for 25 min). Increases in CVC induced by the first and second 100 µm isoproterenol were attenuated by l-NNA alone, and those in response to all doses of isoproterenol were reduced by l-NNA with co-infusion of ketorolac (all P ≤ 0.05). Ketorolac alone augmented increases in CVC induced by 10 µm and by the second 100 µm isoproterenol (both P ≤ 0.05). While isoproterenol-induced sweating was not affected by the separate administration of l-NNA or ketorolac (all P > 0.05), their combined administration augmented sweating elicited by the first 3 min of 100 µm isoproterenol (P = 0.05). We show that while NOS contributes to ß-adrenergic cutaneous vasodilatation, COX restrains the vasodilatation. Finally, combined inhibition of NOS and COX augments ß-adrenergic sweating.

The effect of zilpaterol hydrochloride supplementation on energy metabolism and nitrogen and carbon retention of steers fed at maintenance and fasting intake levels.

An indirect calorimetry trial examined energy metabolism, apparent nutrient digestibility, C retention (CR), and N retention (NR) of cattle supplemented with zilpaterol hydrochloride (ZH). Beef steers ( = 20; 463 ± 14 kg) blocked ( = 5) by weight and source were individually fed and adapted to maintenance energy intake for 21 d before allotment to ZH (90 mg/steer∙d) or no ß-adrenergic agonist treatment (control [CONT]) for 20 d (455 ± 14 kg at the start of treatment). Respiration chambers = 4 were used to quantify heat production (HP) during maintenance (d 12 to 16 of the ZH period) and fasting heat production (FHP; d 19 to 20 of ZH period; total 4 d of fast). Steers were harvested after a 6-d ZH withdrawal and carcasses were graded 24 h after harvest. Control cattle lost more BW ( < 0.01; 9 kg for CONT and 2 kg for ZH-treated) during maintenance whereas the BW loss of ZH-treated steers was greater ( < 0.01; 9 kg for ZH-treated and vs. 4 kg, for CONT) during FHP; no differences ( ≥ 0.76) were detected for G:F, ADG, and end BW. No differences in DMI, apparent nutrient digestibility, O consumption, or CH production ( ≥ 0.12) were detected; however, ZH-treated cattle had greater CO production during maintenance ( = 0.04; 23.6 L/kgBW for ZH-treated and 22.4 L/kg BW for CONT). Digestible energy and ME did not differ ( ≥ 0.19); however, urinary energy was greater ( = 0.05; 0.091 Mcal for CONT and 0.074 Mcal for ZH-treated) in CONT cattle. Steers treated with ZH tended to have greater HP ( = 0.09; 12.44 Mcal for ZH-treated and 11.69 Mcal for CONT), but the effect was reduced on a BW basis ( = 0.12; 0.126 Mcal/kg BW0.75 for ZH-treated and 0.120 Mcal/kg BW0.75 for CONT vs. 0.120 Mcal/kg BW). No treatment difference in FHP was observed ( ≥ 0.32) although CO production (L/steer) increased with ZH treatment ( = 0.04; 1,423 L/steer for ZH-treated and 1,338 L/steer for CONT). Control cattle excreted more ( = 0.05) N in urine (39.8 g/d for CONT and 32.4 g/d for ZH-treated); therefore, NR ( = 0.07; 22.14 g/d for ZH-treated and 14.12 g/d for CONT steers) tended to be greater for ZH-fed steers. Steers treated with ZH lost more C via CO ( = 0.04; 1,036.9 g/d for ZH-treated and 974.3 g/d for CONT) although total CR did not differ ( ≥ 0.23). Empty BW, HCW, and harvest yields (g/kg empty BW) were not different ( ≥ 0.13), whereas ZH increased dressed yield ( = 0.02; 62.12 % for ZH-treated and 60.65% for CONT) and LM area ( = 0.02; 77.81 cm for ZH-treated and vs. 70.90 cm for CONT). Separable carcass lean and actual skeletal muscle protein (SMP) were increased with ZH ( ≤ 0.04; 201.6 and 41.2 kg, respectively for ZH-treated and 196.0 and 38.4 kg, respectively for CONT). Results from this trial indicate that ZH treatment increased ( = 0.03) SMP and tended ( ≥ 0.07) to increase NR and modify HP during maintenance by increasing CO production.

The effects of increasing supplementation of zinc-amino acid complex on growth performance, carcass characteristics, and inflammatory response of beef cattle fed ractopamine hydrochloride.

Forty-two Angus crossbred steers (380 ± 5.3 kg) were enrolled in a finishing study to evaluate the influence of a supplemental Zn amino-acid complex (ZnAA; Availa-Zn) on performance and carcass characteristics of finishing steers in combination with ractopamine hydrochloride (RAC). Steers were stratified by BW into 7 pens of 6 steers each, and individual feed intake was measured. Steers were assigned to 1 of 4 treatments for 86 d (pre-RAC period): a dry-rolled corn-based diet supplemented with 60 mg Zn/kg DM from ZnSO and no supplemental ZnAA (CON; analyzed 88 mg Zn/kg DM; = 6) or CON diet supplemented with 30 (Zn30; = 12), 60 (Zn60; = 12), or 90 (Zn90; = 11) mg Zn/kg DM from ZnAA. Day 86 BW and G:F displayed a quadratic tendency ( = 0.09) with Zn60 steers being greater than the other treatments. Plasma cyclic adenosine monophosphate tended to linearly increase with increasing ZnAA ( = 0.10). On d 88, 6 of 12 steers (one of the 2 pens) receiving supplemental ZnAA was randomly selected to be supplemented with RAC at 300 mg∙steer∙d for the final 28 d of the experiment (RAC period). This created 7 final treatments: CON: no supplemental ZnAA, no RAC ( = 5); Zn30: Zn30, no RAC ( = 5); Zn30R: Zn30 + RAC ( = 6); Zn60: Zn60, no RAC ( = 6); Zn60R: Zn60 + RAC ( = 6); Zn90: Zn90, no RAC ( = 5); and Zn90R: Zn90 + RAC ( = 6). During the RAC period, as supplemental ZnAA increased within RAC-supplemented treatments, there was a linear increase in final BW, ADG, and G:F ( < 0.05). However, there was no effect of supplemental ZnAA on BW, ADG, or G:F during this period in non-RAC fed steers ( ≥ 0.44). Day 111 plasma Cu was increased, plasma Fe decreased, and leukocyte counts and serum interleukin-8 concentrations were greater ( < 0.05) in RAC-fed steers suggesting that RAC may elicit a mild inflammatory response. There was a tendency for increasing Zn supplementation to decrease plasma haptoglobin within RAC-fed steers ( = 0.07), suggesting that Zn may alter the inflammatory response. Overall, Zn60 improved growth performance during the pre-RAC period. Zinc supplemented as ZnAA appears to improve growth in combination with RAC supplementation, suggesting that Zn may enhance or support the biological function of RAC. Additionally, these results indicate that feeding RAC impacts trace mineral status, and potentially causes a non-specific inflammatory response, but further research is required to define this response.

Effect of ractopamine hydrochloride and zilpaterol hydrochloride on cardiac electrophysiologic and hematologic variables in finishing steers.

OBJECTIVE To investigate the effects of dietary supplementation with the ß-adrenoceptor agonists ractopamine hydrochloride and zilpaterol hydrochloride on ECG and clinicopathologic variables of finishing beef steers. DESIGN Randomized controlled trial. ANIMALS 30 Angus steers. PROCEDURES Steers were grouped by body weight and randomly assigned to receive 1 of 3 diets for 23 days: a diet containing no additive (control diet) or a diet containing ractopamine hydrochloride (300 mg/steer/d) or zilpaterol hydrochloride (8.3 mg/kg [3.8 mg/lb] of feed on a dry-matter basis), beginning on day 0. Steers were instrumented with an ambulatory ECG monitor on days -2, 6, 13, and 23, and continuous recordings were obtained for 72, 24, 24, and 96 hours, respectively. At the time of instrumentation, blood samples were obtained for CBC and serum biochemical and blood lactate analysis. Electrocardiographic recordings were evaluated for mean heart rate and arrhythmia rates. RESULTS Steers fed zilpaterol or ractopamine had greater mean heart rates than those fed the control diet. Mean heart rates were within reference limits for all steers, with the exception of those in the ractopamine group on day 14, in which mean heart rate was high. No differences in arrhythmia rates were identified among the groups, nor were any differences identified when arrhythmias were classified as single, paired, or multiple (> 2) beats. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that dietary supplementation of cattle with ractopamine or zilpaterol at FDA-approved doses had no effect on arrhythmia rates but caused an increase in heart rate that remained within reference limits.

Effects of long-term active immunization with the second extracellular loop of human ß1- or ß3-adrenoceptors in thoracic aorta and mesenteric arteries in Lewis rats.

OBJECTIVE: To evaluate whether active immunization producing ß1- or ß3-antibodies (ß1-ABs and ß3-ABs) detected in sera of patients with dilated cardiomyopathies has deleterious effects on vascular reactivity in Lewis rat thoracic aorta (TA) and small mesenteric arteries (SMA). DESIGN AND METHOD: Lewis rats were immunized for 6months with peptidic sequences corresponding to the second extracellular loop of ß1- and ß3-adrenoceptors (ARs). During the immunization, systolic blood pressure (SBP) was monitored using the tail cuff method. The vascular reactivity of immunized rats was assessed by ex vivo studies on SMA and TA using various ß-AR agonists, phenylephrine and KCl. RESULTS: The immunizations producing functional ß1-ABs and ß3-ABs did not affect the SBP. However, in TA from ß1-AR-immunized rats, the relaxations mediated by dobutamine and salbutamol were significantly impaired in comparison with adjuvant rats whereas nebivolol-induced relaxation was not modified. Moreover, phenylephrine and KCl-mediated contractions were enhanced in these rats. In contrast, immunization with ß3-AR peptide led to the increase of relaxations induced by dobutamine in TA but did not change those induced by salbutamol and nebivolol. Surprisingly, in SMA from both rats immunized with ß1- or ß3-peptides, relaxations induced by the various ß-agonists were not changed whereas phenylephrine and KCl-mediated contractions were impaired. CONCLUSIONS: Our study shows that ß1- and ß3-ABs can affect vascular reactivity. ß1-ABs would have a pathogenic action whereas ß3-ABs would have a beneficial effect on aorta reactivity.

The metabolic, stress axis, and hematology response of zilpaterol hydrochloride supplemented beef heifers when exposed to a dual corticotropin-releasing hormone and vasopressin challenge.

The objective of this study was to determine the metabolic, stress, and hematology response of beef heifers supplemented with zilpaterol hydrochloride (ZH) when exposed to an endocrine stress challenge. Heifers ( = 20; 556 ± 7 kg BW) were randomized into 2 treatment groups: 1) control (CON), no ZH supplementation, and 2) zilpaterol (ZIL), supplemented with ZH at 8.33 mg/kg (DM basis). The ZIL group was supplemented ZH for 20 d, with a 3-d withdrawal period. On d 24, heifers received an intravenous bolus of corticotropin-releasing hormone (CRH; 0.3 µg/kg BW) and arginine vasopressin (VP; 1.0 µg/kg BW) to activate the stress axis. Blood samples were collected at 30-min intervals for serum and 60-min intervals for plasma and whole blood, from -2 to 8 h relative to the challenge at 0 h (1000 h). Samples were analyzed for glucose, insulin, NEFA, blood urea nitrogen (BUN), cortisol, epinephrine, norepinephrine, and complete blood cell counts. Following the challenge, cattle were harvested over a 3-d period. Liver, LM, and biceps femoris (BF) samples were collected and analyzed for glucose, lactate, and glycolytic potential (GP). There was a treatment ( ≤ 0.001) effect for vaginal temperature (VT), with ZIL having a 0.1°C decrease in VT when compared with CON. A treatment × time effect ( = 0.002) was observed for NEFA. A treatment effect was observed for BUN; ZIL had decreased BUN concentrations compared with CON ( < 0.001) prior to the challenge; however, no treatment × time effect was observed. There was also a treatment effect for cortisol ( ≤ 0.01) and epinephrine ( = 0.003); ZIL had decreased cortisol and epinephrine during the CRH/VP challenge when compared with CON. There was a time effect for total white blood cells, lymphocytes, and monocytes; each variable increased ( ≤ 0.01) 2 h postchallenge. Additionally, neutrophil counts decreased ( ≤ 0.01) in response to CRH/VP challenge in both treatment groups. Glucose concentrations within the LM were greater ( = 0.03) in CON when compared with ZIL. Lactate concentrations and GP within the BF were greater in CON ( = 0.05) when compared with ZIL. These data suggest there are some variations observed between treatments in terms of response to the CRH/VP challenge; however, in the environmental conditions of this trial, none of the variations observed suggest that the supplementation of ZH detrimentally alters the ability of cattle to effectively respond to stressful stimuli.

Effects of isoxsuprine hydrochloride on electrocardiographic and trace element status in sheeps.

OBJECTIVE: To study the effect of isoxsuprine hydrochloride on the ischaemic electrocardiographic change and trace element status in sheep. METHODS: This study was conducted from March 16 to 23, 2012, at Istanbul University, Turkey, and comprised sheep aged 6 months. The animals were divided into two equal groups. The control group was fed a standard diet and had free access to water. In the experimental group, isoxsuprine hydrochloride was injected at a dose of 0.6 mg/kg through the intramuscular route. Electrocardiographic changes, including creatine kinase and cardiac troponin-I, and serum levels of selenium, copper, calcium, magnesium, iron and zinc were investigated in healthy sheep. SPSS 15 was used for statistical analysis. RESULTS: The 14 sheep were divided into two groups of 7(50%) each. The overall mean weight of the study population was 35±10kg. Selenium, calcium, iron and zinc concentrations did not show any difference in serum samples (p>0.05). However, copper and magnesium concentrations decreased in serum after the administration of the drug (p<0.05). In the experimental group, ST segment depression and abnormal T-wave was found in 6(86%) animals within 60min. CONCLUSIONS: Isoxsuprine hydrochloride increased cardiotoxicity risk in sheep.