Vascular region-specific changes in arterial tone in rats with type 2 diabetes mellitus: Opposite responses of mesenteric and femoral arteries to acetylcholine and 5-hydroxytryptamine.

AIMS: Type 2 diabetes mellitus (T2DM) ranks in the top 10 causes of mortality worldwide. The key factor of T2DM vascular complications is endothelial dysfunction. It is characterized by the vessels motor activity disruption and endothelium-derived factors imbalance. The blood vessels morphological and molecular heterogeneity greatly affects the changes occurring in T2DM. Therefore, we conducted a comparative study of vascular bed changes occurring in T2DM. MAIN METHODS: Male Wistar rats were fed a high-fat diet for 20 weeks, followed by a single streptozotocin injection (20 mg/kg). T2DM was confirmed with an oral glucose tolerance test. KEY FINDINGS: A dose-dependent contraction study showed an increase in third-order mesenteric arterioles response to serotonin but not to phenylephrine. These vessels also exhibited a decrease in acetylcholine-dependent relaxation and an increase in guanylate cyclase function. At the same time, the femoral arteries showed a tendency for increased acetylcholine-dependent relaxation. The blood plasma analysis revealed low bioavailable nitric oxide and high levels of endothelin-1 and ROS. SIGNIFICANCE: This knowledge, in conjunction with the features of the T2DM course, can allow further targeted approaches development for the prevention and treatment of vascular complications occurring in the disease.

Oxytocin receptor antagonists as a novel pharmacological agent for reducing smooth muscle tone in the human prostate.

Pharmacotherapies for the treatment of Benign Prostatic Hyperplasia (BPH) are targeted at reducing cellular proliferation (static component) or reducing smooth muscle tone (dynamic component), but response is unpredictable and many patients fail to respond. An impediment to identifying novel pharmacotherapies is the incomplete understanding of paracrine signalling. Oxytocin has been highlighted as a potential paracrine mediator of BPH. To better understand oxytocin signalling, we investigated the effects of exogenous oxytocin on both stromal cell proliferation, and inherent spontaneous prostate contractions using primary models derived from human prostate tissue. We show that the Oxytocin Receptor (OXTR) is widely expressed in the human prostate, and co-localises to contractile cells within the prostate stroma. Exogenous oxytocin did not modulate prostatic fibroblast proliferation, but did significantly (p < 0.05) upregulate the frequency of spontaneous contractions in prostate tissue, indicating a role in generating smooth muscle tone. Application of atosiban, an OXTR antagonist, significantly (p < 0.05) reduced spontaneous contractions. Individual tissue responsiveness to both exogenous oxytocin (R2 = 0.697, p < 0.01) and atosiban (R2 = 0.472, p < 0.05) was greater in tissue collected from older men. Overall, our data suggest that oxytocin is a key regulator of inherent spontaneous prostate contractions, and targeting of the OXTR and associated downstream signalling is an attractive prospect in the development of novel BPH pharmacotherapies.

Effects of the herbal preparation STW 5-II on in vitro muscle activity in the guinea pig stomach.

BACKGROUND: STW 5 is a combination of nine medicinal herbal extracts and used to treat functional gastrointestinal disorders including functional dyspepsia. It has a region-specific effect by relaxing the proximal and contracting the distal stomach. The research combination STW 5-II (Iberogast® Advance) lacks three herbal extracts but seems clinically as effective as STW 5. However, the action of STW 5-II on gastric motility is unknown. METHODS: In vitro circular and longitudinal muscle tone and contractility were recorded from guinea pig gastric fundus and antrum with isometric force transducers. KEY RESULTS: STW 5-II decreased concentration-dependently (64-512 µg/ml) the tone of circular and longitudinal muscle strips from the fundus. In contrast, STW 5-II increased concentration-dependently contraction amplitude in antral circular and longitudinal muscle. The effects were region-dependent but comparable in the two muscle layers. Application of 512 µg STW 5 or STW 5-II revealed comparable effects in the fundus and antrum circular and longitudinal muscle strips. CONCLUSIONS AND INTERFERENCES: STW 5-II had a region-specific effect and relaxed the proximal stomach but increased the contractility in the antrum. It was as effective as STW 5 which may explain its comparable clinical effects in treating functional dyspepsia. Impaired accommodation may be normalized through relaxation of the fundus, while the motility-promoting effects leading to an increase in antral motility may activate the gastric pump.

Dinámica contráctil inducida por p-clorofenol alcanforado en anillos aórticos de ratas Wistar / Dinâmica contrátil induzida por cânfora-clorofenol em anéis aórticos de ratos Wistar / Camphorated p-chlorophenol-induced contractile dynamics in aortic rings of Wistar rats

Introducción: El p-clorofenol alcanforado es un derivado clorofenólico de uso común como medicación intraconducto en Endodoncia. Son escasos los reportes científicos sobre sus efectos en la musculatura lisa vascular arterial y la regulación del flujo sanguíneo local. Objetivo: Determinar el efecto del p-clorofenol alcanforado sobre la dinámica contráctil del músculo liso vascular arterial en el tiempo. Método: Se realizó una investigación experimental preclínica utilizando 14 anillos de aorta obtenidos de ratas Wistar. Los anillos se colocaron en baño de órganos y se preactivaron con noradrenalina, registrándose luego la tensión desarrollada por el músculo liso vascular tras la adición de p-clorofenol alcanforado durante diferentes intervalos de tiempo. Resultados: El 51,4 porciento de la musculatura lisa vascular se relajó por la acción del p-clorofenol alcanforado. El mayor descenso del tono vascular se produjo entre el tercer y quinto minuto de añadido el medicamento. Las pruebas de Wilcoxon de los rangos con signos evidenciaron diferencias significativas entre la tensión base inicial y la registrada en los diferentes intervalos de tiempo estudiados. Conclusiones: el p-clorofenol alcanforado, induce in vitro, relajación del músculo liso arterial a través de un acoplamiento excitación-contracción de tipo farmacomecánico, la cual se incrementa en función del tiempo(AU).

Introduction: Camphorated p-chlorophenol is a chlorophenolic derivative commonly used as an intra-oral medication in endodontics. Scientific reports on its effects in arterial vascular smooth muscle and local blood flow regulation are scarce. Objective: To determine the effect of camphorated p-chlorophenol on the contractile dynamics of arterial vascular smooth muscle. Method: An experimental and preclinical research was conducted with the use of 14 aortic rings of Wistar rats. The rings were placed in an organ bath and preactivated with noradrenaline, and the tension developed by the vascular smooth muscle at different time intervals was recorded after induction of camphorated p-chlorophenol. Results: Most of the vascular smooth muscle (51.4 percent) relaxed with the use of camphorated p-chlorophenol. The greatest decrease in vascular tone occurred between the third and fifth minute after use the drug. Wilcoxon rank tests showed significant differences between tension observed at baseline and those recorded at the different time intervals studied. Conclusions: Camphorated p-chlorophenol, induces in vitro, relax the arterial smooth muscle through a pharmacomechanical excitation-contraction link, which increases according to the time(AU).

Introdução: O cânfora-clorofenol é um derivado clorofenólico comumente utilizado como medicamento intracanal em Endodontia. Relatórios científicos sobre seus efeitos no músculo liso vascular arterial e na regulação do fluxo sanguíneo local são escassos. Objetivo: Determinar o efeito da cânfora-clorofenol na dinâmica contrátil do músculo liso vascular arterial ao longo do tempo. Método: Foi realizada investigação experimental pré-clínica com 14 anéis aórticos obtidos de ratos Wistar. Os anéis foram colocados em banho de órgãos e pré-ativados com norepinefrina, em seguida, a tensão desenvolvida pela musculatura lisa vascular foi registrada após a adição de cânfora-clorofenol em diferentes intervalos de tempo. Resultados: 51,4 porcento dos músculos lisos vasculares estavam relaxados pela ação do cânfora-clorofenol. A maior diminuição do tônus vascular ocorreu entre o terceiro e o quinto minuto após a adição do medicamento. Os testes de Wilcoxon das faixas com sinais mostraram diferenças significativas entre a tensão base inicial e a registrada nos diferentes intervalos de tempo estudados. Conclusões: O cânfora-clorofenol induz, in vitro, relaxamento da musculatura lisa arterial por meio de um acoplamento excitação-contração do tipo farmacomecânico, que aumenta em função do tempo(AU).

Moderate substrate stiffness induces vascular smooth muscle cell differentiation through cellular morphological and tensional changes.

BACKGROUND: Vascular smooth muscle cells (VSMCs) are one of the main components of arterial walls and actively remodel the arterial walls in which they reside through biomechanical signals applied to themselves. Contractile or differentiated VSMCs have been observed in normal blood vessels. In pathological vascular conditions, they become dedifferentiated from contractile to non-contractile or synthetic cells, and a similar change is observed when VSMCs are placed in culture conditions. The mechanisms regulating VSMC differentiation remain unclear at this stage. OBJECTIVE: In this paper we investigated the effects of substrate stiffness on the morphology, intercellular tension, and differentiation of VSMCs. METHODS: Rat VSMCs were cultured on polyacrylamide (PA) gels, with elastic moduli of 15 kPa, 40 kPa, and 85 kPa, and PDMS substrate with elastic modulus of 1 MPa, and their morphology, intercellular tension, and contractile differentiation were assessed. RESULTS: Using fluorescence microscope image-based analysis and nano-indentation imaging with atomic force microscopy, we found that cell spreading and stiffening were induced by substrate stiffening in VSMCs. Interestingly, VSMCs on PA gel substrates with medium stiffness (40 kPa) showed significant elongation and shape polarization, and their 𝛼-SMA with F-actin cytoskeleton expression ratio was significantly higher than those of cells on other substrates. CONCLUSION: The results indicate an existing optimal substrate stiffness for promoting VSMC differentiation, and also indicate that cell shape polarization might be a key factor for VSMC differentiation.

Etifoxine does not impair muscle tone and motor function in rats as assessed by in vivo and in vitro methods.

The purpose of our study is to evaluate the effects of the translocator protein (TSPO) ligand etifoxine on muscle tone and locomotor activity. In addition, the mechanism of action of etifoxine on the presynaptic membrane and neuromuscular junction is investigated. These effects of etifoxine were examined employing the following methods: 1) in vivo experiments using bar holding test and activity cage test, and 2) comparative in vitro studies with nifedipine on indirectly-elicited twitches of striated abdominal muscle preparations. Etifoxine in doses 50 mg/kg and 100 mg/kg i.p. does not produce any significant changes in locomotor activity and muscle tone of intact rats. Nifedipine (10-5 М) induces a significant decrease in the muscle force of striated muscle preparations. Etifoxine (10-8-10-4 М) has no significant effect on indirectly-elicited twitch tension. Results show that the TSPO ligand etifoxine has no myorelaxant effect. The activation of TSPO is not associated with a reduction in muscle tone and motor impairment. Etifoxine does not affect the presynaptic membrane and its influence on L-type Ca2+-channels is insignificant. Etifoxine does not act as a competitive antagonist of acetylcholine and does not impair the impulse transmission in the neuromuscular junction.

Paraffin therapy induces a decrease in the passive stiffness of gastrocnemius muscle belly and Achilles tendon: A randomized controlled trial.

BACKGROUND: The purposes of this study were to examine the feasibility of using the MyotonPRO digital palpation device in measuring the passive stiffness of gastrocnemius muscle belly and Achilles tendon; to determine between-days test-retest reliability of MyotonPRO; and to evaluate the acute effect of paraffin therapy on stiffness measurements in healthy participants. METHODS: It is a randomized controlled trial. Twenty healthy participants (male, n = 10; female, n = 10; total, n = 20) were recruited to evaluate the passive stiffness of gastrocnemius muscle belly and Achilles tendon. Dominant and nondominant legs were randomly divided into an experimental side (20 cases) and a control side (20 cases). The experimental side received 20 minutes of paraffin therapy. RESULTS: The stiffness of muscle and tendon in the experimental side decreased significantly after paraffin therapy (P < .01), whereas no significant differences in stiffness measurements were found in the control side (P > .05). The passive stiffness of muscle and tendon was positively correlated with the ankle from 30° plantar flexion to10° dorsiflexion for dominant legs. Between-days test-retest reliability in stiffness measurements was high or very high (ICCs were above 0.737). CONCLUSION: Paraffin therapy induces a decrease in the passive stiffness of gastrocnemius muscle belly and Achilles tendon. Furthermore, the MyotonPRO can reliably determine stiffness measurements.

Treatment of Disorders of Tone and Other Considerations in Pediatric Movement Disorders.

Pediatric movement disorders (PMDs) consist of a heterogeneous group of signs and symptoms caused by numerous neurological diseases. Different neurological disorders in children also share overlapping movement disorders making a diagnosis of the underlying cause of the movement disorder challenging. The similarity of the symptoms across multiple disease types suggests that there may be a final common motor pathway causing the overlapping movement disorders. There are numerous disorders in children associated with disturbances in tone and involuntary movements. This chapter will focus primarily on those disorders that involve abnormalities of tone and other important considerations of pediatric movement disorders. This chapter will address rating scales and goals for treatment and will include a review of symptomatic treatment and, where possible, the treatment of the underlying disease processes. The chapter will review representative disorders, including an inborn error of metabolism, an autoimmune disorder, and a group of neurodegenerative disorders. These examples demonstrate how the disorder's underlying pathophysiology results in a specific approach to the underlying disease and the associated conditions of tone and involuntary movements. Finally, the multiple treatment options for cerebral palsy and considerations of cerebral palsy mimics will be discussed.

Acetaminophen increases pulmonary and systemic vasomotor tone in the newborn rat.

BACKGROUND: Acetaminophen is widely prescribed to both neonates and young children for a variety of reasons. In adults, therapeutic usage of acetaminophen induces systemic arterial pressure changes and exposure to high doses promotes tissue toxicity. The pulmonary vascular effects of acetaminophen at any age are unknown. Hypothesizing that, early in life, it promotes vasomotor tone changes via oxidative stress, we tested the in vitro acetaminophen effects on intrapulmonary and carotid arteries from newborn and adult rats. METHOD: We measured the acetaminophen dose-response in isometrically mounted arteries and pharmacologically evaluated the factors accounting for its vasomotor effects. RESULTS: Acetaminophen induced concentration- and age-dependent vasomotor tone changes. Whereas a progressive increase in vasomotor tone was observed in the newborn, the adult arteries showed mostly vasorelaxation. Inhibition of endogenous nitric oxide generation with L-NAME and the use of the peroxynitrite decomposition catalyst FeTPPS (Fe(III)5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato chloride) mostly abolished the drug-induced increase in newborn pulmonary vasomotor tone CONCLUSIONS: In newborn rats, acetaminophen increases pulmonary vasomotor tone via peroxynitrite generation. Given its therapeutic usage, further clinical studies are warranted to assess the acetaminophen effects on the newborn pulmonary and systemic vascular resistance.

Differential expression of angiotensin II type 1 receptor subtypes within the cerebral microvasculature.

Arteries and arterioles constrict in response to intraluminal pressure to generate myogenic tone, but the molecular nature of the vascular force-sensing mechanism is not fully characterized. Here, we investigated the role of angiotensin II type 1 receptors (AT1Rs) on vascular smooth muscle cells in the development of myogenic tone in cerebral parenchymal arterioles from mice. We found that pretreatment with the AT1R blocker losartan inhibited the development of myogenic tone in these vessels but did not alter the luminal diameter of arterioles with preestablished tone. Rodents express two AT1R isotypes: AT1Ra and AT1Rb. We previously demonstrated that AT1Rb is expressed at much higher levels compared with AT1Ra in cerebral pial arteries and is required for myogenic contractility in these vessels, whereas AT1Ra is unnecessary for this function. Here, we found that AT1Ra and AT1Rb are expressed at similar levels in parenchymal arterioles and that genetic knockout of AT1Ra blunted the ability of these vessels to generate myogenic tone. We also found that AT1Rb and total AT1R expression levels are much lower in parenchymal arterioles compared with pial arteries and that parenchymal arterioles are less sensitive to the vasoconstrictive effects of the endogenous AT1R ligand angiotensin II (ANG II). We conclude that 1) AT1Rs are critical for the initiation, but not the maintenance, of myogenic tone in parenchymal arterioles, and 2) lower levels of AT1Rb and total AT1R in parenchymal arterioles compared with pial arteries result in differences in myogenic and ANG II-induced vasoconstriction between these vascular segments.NEW & NOTEWORTHY Myogenic tone is critical for appropriate regulation of cerebral blood flow, but the mechanisms used by vascular smooth muscle cells to detect changes in intraluminal pressure are not fully characterized. Here, we demonstrate angiotensin II receptor type 1 (AT1R) is indispensable to initiation, but not maintenance, of myogenic tone in cerebral parenchymal arterioles. Furthermore, we demonstrate differences in AT1R expression levels lead to critical differences in contractile regulation between parenchymal arterioles and cerebral pial arteries.

Agonism of the TMEM16A calcium-activated chloride channel modulates airway smooth muscle tone.

TMEM16A (anoctamin 1) is an important calcium-activated chloride channel in airway smooth muscle (ASM). We have previously shown that TMEM16A antagonists such as benzbromarone relax ASM and have proposed TMEM16A antagonists as novel therapies for asthma treatment. However, TMEM16A is also expressed on airway epithelium, and TMEM16A agonists are being investigated as novel therapies for cystic fibrosis. There are theoretical concerns that agonism of TMEM16A on ASM could lead to bronchospasm, making them detrimental as airway therapeutics. The TMEM16A agonist Eact induced a significant contraction of human ASM and guinea pig tracheal rings in an ex vivo organ bath model. Pretreatment with two different TMEM16A antagonists, benzbromarone or T16Ainh-A01, completely attenuated these Eact-induced contractions. Pretreatment with Eact alone augmented the maximum acetylcholine contraction. Pretreatment of A/J mice in vivo with nebulized Eact caused an augmentation of methacholine-induced increases in airway resistance measured by the forced oscillatory technique (flexiVent). Pretreatment with the TMEM16A antagonist benzbromarone significantly attenuated methacholine-induced increases in airway resistance. In in vitro cellular studies, TMEM16A was found to be expressed more abundantly in ASM compared with epithelial cells in culture (8-fold higher in ASM). Eact caused an increase in intracellular calcium in human ASM cells that was completely attenuated by pretreatment with benzbromarone. Eact acutely depolarized the plasma membrane potential of ASM cells, which was attenuated by benzbromarone or nifedipine. The TMEM16A agonist Eact modulates ASM contraction in both ex vivo and in vivo models, suggesting that agonism of TMEM16A may lead to clinically relevant bronchospasm.

Role of TRPP2 in mouse airway smooth muscle tension and respiration.

The transient receptor potential polycystin-2 (TRPP2) is encoded by the Pkd2 gene, and mutation of this gene can cause autosomal dominant polycystic kidney disease (ADPKD). Some patients with ADPKD experience extrarenal manifestations, including radiologic and clinical bronchiectasis. We hypothesized that TRPP2 may regulate airway smooth muscle (ASM) tension. Thus, we used smooth muscle-Pkd2 conditional knockout (Pkd2SM-CKO) mice to investigate whether TRPP2 regulated ASM tension and whether TRPP2 deficiency contributed to bronchiectasis associated with ADPKD. Compared with wild-type mice, Pkd2SM-CKO mice breathed more shallowly and faster, and their cross-sectional area ratio of bronchi to accompanying pulmonary arteries was higher, suggesting that TRPP2 may regulate ASM tension and contribute to the occurrence of bronchiectasis in ADPKD. In a bioassay examining isolated tracheal ring tension, no significant difference was found for high-potassium-induced depolarization of the ASM between the two groups, indicating that TRPP2 does not regulate depolarization-induced ASM contraction. By contrast, carbachol-induced contraction of the ASM derived from Pkd2SM-CKO mice was significantly reduced compared with that in wild-type mice. In addition, relaxation of the carbachol-precontracted ASM by isoprenaline, a ß-adrenergic receptor agonist that acts through the cAMP/adenylyl cyclase pathway, was also significantly attenuated in Pkd2SM-CKO mice compared with that in wild-type mice. Thus, TRPP2 deficiency suppressed both contraction and relaxation of the ASM. These results provide a potential target for regulating ASM tension and for developing therapeutic alternatives for some ADPKD complications of the respiratory system or for independent respiratory disease, especially bronchiectasis.

Biological characterization of new inhibitors of microsomal PGE synthase-1 in preclinical models of inflammation and vascular tone.

BACKGROUND AND PURPOSE: Microsomal PGE synthase-1 (mPGES-1), the inducible synthase that catalyses the terminal step in PGE2 biosynthesis, is of high interest as therapeutic target to treat inflammation. Inhibition of mPGES-1 is suggested to be safer than traditional NSAIDs, and recent data demonstrate anti-constrictive effects on vascular tone, indicating new therapeutic opportunities. However, there is a lack of potent mPGES-1 inhibitors lacking interspecies differences for conducting in vivo studies in relevant preclinical disease models. EXPERIMENTAL APPROACH: Potency was determined based on the reduction of PGE2 formation in recombinant enzyme assays, cellular assay, human whole blood assay, and air pouch mouse model. Anti-inflammatory properties were assessed by acute paw swelling in a paw oedema rat model. Effect on vascular tone was determined with human ex vivo wire myography. KEY RESULTS: We report five new mPGES-1 inhibitors (named 934, 117, 118, 322, and 323) that selectively inhibit recombinant human and rat mPGES-1 with IC50 values of 10-29 and 67-250 nM respectively. The compounds inhibited PGE2 production in a cellular assay (IC50 values 0.15-0.82 µM) and in a human whole blood assay (IC50 values 3.3-8.7 µM). Moreover, the compounds blocked PGE2 formation in an air pouch mouse model and reduced acute paw swelling in a paw oedema rat model. Human ex vivo wire myography analysis showed reduced adrenergic vasoconstriction after incubation with the compounds. CONCLUSION AND IMPLICATIONS: These mPGES-1 inhibitors can be used as refined tools in further investigations of the role of mPGES-1 in inflammation and microvascular disease.

Efficacy and Safety of Botulinum Toxin Type A for Limb Spasticity after Stroke: A Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: Inconsistent data have been reported for the effectiveness of intramuscular botulinum toxin type A (BTXA) in patients with limb spasticity after stroke. This meta-analysis of available randomized controlled trials (RCTs) aimed to determine the efficacy and safety of BTXA in adult patients with upper and lower limb spasticity after stroke. METHODS: An electronic search was performed to select eligible RCTs in PubMed, Embase, and the Cochrane library through December 2018. Summary standard mean differences (SMDs) and relative risk (RR) values with corresponding 95% confidence intervals (CIs) were employed to assess effectiveness and safety outcomes, respectively. RESULTS: Twenty-seven RCTs involving a total of 2,793 patients met the inclusion criteria, including 16 and 9 trials assessing upper and lower limb spasticity cases, respectively. For upper limb spasticity, BTXA therapy significantly improved the levels of muscle tone (SMD=-0.76; 95% CI -0.97 to -0.55; P<0.001), physician global assessment (SMD=0.51; 95% CI 0.35-0.67; P<0.001), and disability assessment scale (SMD=-0.30; 95% CI -0.40 to -0.20; P<0.001), with no significant effects on active upper limb function (SMD=0.49; 95% CI -0.08 to 1.07; P=0.093) and adverse events (RR=1.18; 95% CI 0.72-1.93; P=0.509). For lower limb spasticity, BTXA therapy was associated with higher Fugl-Meyer score (SMD=5.09; 95%CI 2.16-8.01; P=0.001), but had no significant effects on muscle tone (SMD=-0.12; 95% CI -0.83 to 0.59; P=0.736), gait speed (SMD=0.06; 95% CI -0.02 to 0.15; P=0.116), and adverse events (RR=1.01; 95% CI 0.71-1.45; P=0.949). CONCLUSIONS: BTXA improves muscle tone, physician global assessment, and disability assessment scale in upper limb spasticity and increases the Fugl-Meyer score in lower limb spasticity.

Effects of Paeoniflorin on the activity of muscle strips, intracellular calcium ion concentration and L­type voltage­sensitive calcium ion channels in the sphincter of Oddi of hypercholesterolemic rabbits.

Sphincter of Oddi dysfunction (SOD) is a benign obstructive disorder predominantly resulting from spasms of the SO. Pharmacological therapies aim to induce SO relaxation; the hypercholesterolemic (HC) rabbit is the only SOD model available for study. In the present study, SO muscle strips, intracellular calcium ion concentrations and the mRNA expression levels of the α1C subunit of the L­type calcium channel in the SO muscle cells of HC rabbits were employed to investigate the effects of paeoniflorin (PF). Alterations in L­type calcium channel α subunit 1C mRNA and protein expression in SO cells with HC following the application of different concentrations of PF were determined by reverse transcription­quantitative polymerase chain reaction and western blotting. The whole cell patch clamp technique was used to observe the effects of different concentrations of paeoniflorin on L­type calcium channel current. The results of the present study demonstrated that PF induced the relaxation of SO muscle strips and reduced the intracellular calcium concentration in the SO muscle cells of HC rabbits. In addition, PF decreased the mRNA expression levels of the α1C subunit of the L­type calcium channel and reduced the L­type calcium channel current in SO cells. These results suggested that the mechanism underlying the relaxation of the SO muscle by PF may be associated with the reduction of calcium ion influx via L­type calcium channels.

An assessment of KIR channel function in human cerebral arteries.

In the rodent cerebral circulation, inward rectifying K+ (KIR) channels set resting tone and the distance over which electrical phenomena spread along the arterial wall. The present study sought to translate these observations into human cerebral arteries obtained from resected brain tissue. Computational modeling and a conduction assay first defined the impact of KIR channels on electrical communication; patch-clamp electrophysiology, quantitative PCR, and immunohistochemistry then characterized KIR2.x channel expression/activity. In keeping with rodent observations, computer modeling highlighted that KIR blockade should constrict cerebral arteries and attenuate electrical communication if functionally expressed. Surprisingly, Ba2+ (a KIR channel inhibitor) had no effect on human cerebral arterial tone or intercellular conduction. In alignment with these observations, immunohistochemistry and patch-clamp electrophysiology revealed minimal KIR channel expression/activity in both smooth muscle and endothelial cells. This absence may be reflective of chronic stress as dysphormic neurons, leukocyte infiltrate, and glial fibrillary acidic protein expression was notable in the epileptic cortex. In closing, KIR2.x channel expression is limited in human cerebral arteries from patients with epilepsy and thus has little impact on resting tone or the spread of vasomotor responses. NEW & NOTEWORTHY KIR2.x channels are expressed in rodent cerebral arterial smooth muscle and endothelial cells. As they are critical to setting membrane potential and the distance signals conduct, we sought to translate this work into humans. Surprisingly, KIR2.x channel activity/expression was limited in human cerebral arteries, a paucity tied to chronic brain stress in the epileptic cortex. Without substantive expression, KIR2.x channels were unable to govern arterial tone or conduction.

HCN as a Mediator of Urinary Homeostasis: Age-Associated Changes in Expression and Function in Adrenergic Detrusor Relaxation.

The Hyperpolarization activated, cyclic nucleotide gated (HCN) channel is a candidate mediator of neuroendocrine influence over detrusor tonus during filling. In other tissues, HCN loss with aging is linked to declines in rhythmicity and function. We hypothesized that HCN has an age-sensitive expression profile and functional role in adrenergic bladder relaxation. HCN was examined in bladders from young (2-6 months) and old (18-24 months) C57BL/6 female mice, using qRT-PCR, RNAScope, and Western blots. Isometric tension studies were conducted using bladder strips from young wild-type (YWT), old wild-type (OWT), and young HCN1 knock-out (YKO) female mice to test the role HCN in effects of ß-adrenergic stimulation. Hcn1 is the dominant HCN isoform RNA in the mouse bladder wall, and is diminished with age. Location of Hcn RNA within the mouse bladder wall is isoform-specific, with HCN1 limited to the detrusor layer. Passively-tensioned YWT bladder strips are relaxed by isoproterenol in the presence of HCN function, where OWT strips are relaxed only in the presence of HCN blockade. HCN has an age-specific expression and function in adrenergic detrusor relaxation in mouse bladder strips.

Activity of silver nanoparticles on prokaryotic cells and Bothrops jararacussu snake venom.

Nanoparticle-conjugated venom-toxins of venomous animals and its therapeutic efficacy against emerging or neglecting diseases is a promising strategy. In this study, silver nanoparticles (AgNPs ∼50 nm, 0.081 mg mL-1) were studied against the neuromuscular blockade, myotoxic effects induced by Bothrops jararacussu venom (60 µg mL-1) and also against prokaryotic cells. The neurotoxicity was evaluated on ex vivo mouse phrenic nerve-diaphragm using traditional myographic technique, able to obtain functional contractile responses and to check the neurotransmission. The myotoxicity on mammalian cells was evaluated in muscles resulting from pharmacological assays using routine histological techniques and light microscopy. The toxicity to prokaryotic cells was evaluated on Salmonella typhimurium TA100 without metabolic activation. The in vitro preincubation model between AgNPs and venom was enough to abolish toxic effects of B. jararacussu venom, but mammalian cells were highly sensitive to AgNPs more than prokaryotic cells, by acting as dose-independently and dose-dependently parameters, respectively. These results allowed us to conclude that AgNPs showed promising activity as antivenom agent but for its safer use, the toxicity should be evaluated on experimental animals.

Exploration of the establishment of manganese poisoning rat model and analysis of discriminant methods.

OBJECTIVE: We explored methods to establish an animal model of manganese poisoning and evaluate the feasibility of the determination method. METHODS: Twenty-four specific pathogen-free male rats were randomly divided into four groups: control, low-dose (15.0 mg/kg), middle-dose (25.0 mg/kg), and high-dose (50.0 mg/kg). Intraperitoneal injection of MnCl2·H2O was administered every 48 h for three months. Rats were tested for behavior, muscle tension, and with a balance beam experiment at the end of each month. Three months later, the rats were sacrificed and brain tyrosine hydroxylase (TH) expression levels were measured. RESULTS: Rats in each group exhibited changes in behavior, muscle tone, and balance after exposure to manganese, and the scores of each test for the high-dose and middle-dose groups were statistically different from the low-dose and control groups. Finally, a rat model of manganese poisoning was identified with the TH expression less than 30% of the normal value. We find that the modeling success rate of the middle-dose and high-dose groups were 66.67% and 100%, respectively. In addition, there were negative correlations between the three assessment methods such as behavioral tests and TH expression levels. CONCLUSIONS: Intraperitoneal injection of MnCl2·H2O (25 mg/kg) can successfully establish a manganese poisoning rat model with low mortality rate. Muscle tension, balance beam, and behavioral tests can be used as preliminary determination methods for modeling.