NO donor KMUP-1 improves hepatic ischemia-reperfusion and hypoxic cell injury by inhibiting oxidative stress and pro-inflammatory signaling.

This study investigates whether KMUP-1 improves hepatic ischemia-reperfusion (I/R) and hypoxic cell injury via inhibiting Nox2- and reactive oxygen species (ROS)-mediated pro-inflammation. Rats underwent ischemia by occlusion of the portal vein and hepatic artery for 45 minutes. Reperfusion was allowed for 4 h. Serum was used for analysis of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). DNA extracted from liver homogenate was analyzed by electrophoresis to observe the fragmentation. Lipid peroxidation (LPO) was evaluated by measuring thiobarbituric acid-reactive substances (TBARS). NO and ROS contents were measured using Griess reagent and 2'-7'-dichlorofluorescein, respectively. Proteins levels were visualized by Western blotting. Liver damage was observed under a microscope. Intravenous KMUP-1 (0.25, 0.5 and 1 mg/kg) reduced I/R-induced ALT and AST levels, DNA fragmentation, ROS and malondialdehyde (MDA) and restored the NO levels of I/R rats. KMUP-1 protected the liver architecture from worsening of damage and focal sinusoid congestion, increased endothelium NO synthase (eNOS), guanosine 3', 5'cyclic monophosphate (cGMP), protein kinase G (PKG) and the B-cell lymphoma 2/Bcl-2-associated X protein (Bcl-2/Bax) ratio, attenuated phosphodiesterase 5A (PDE-5A) and cleaved caspase-3 expression in I/R-liver. In hypoxic HepG2 cells, KMUP-1 increased cGMP/PKG, restored peroxisome proliferator-activated receptor-gamma (PPAR-gamma) and decreased matrix metalloproteinases-9 (MMP-9), Rho kinase II (ROCK II), hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelium growth factor (VEGF). KMUP-1 protects liver from I/R-injury and hypoxic hepatocytes from apoptosis-associated free radical generation and pro-inflammation by restoring/increasing NO/cGMP/PPAR-gamma, reducing ROS/Nox2 and inhibiting ROCKII/MMP-9.

Eugenolol and glyceryl-isoeugenol suppress LPS-induced iNOS expression by down-regulating NF-kappaB AND AP-1 through inhibition of MAPKS and AKT/IkappaBalpha signaling pathways in macrophages.

Eugenol and isoeugenol, two components of clover oil, have been reported to possess several biomedical properties, such as anti-inflammatory, antimicrobial and antioxidant effects. This study aims to examine the anti-inflammatory effects of eugenol, isoeugenol and four of their derivatives on expression of inducible nitric oxide synthase (iNOS) activated by lipopolysaccharide (LPS) in mouse macrophages (RAW 264.7), and to investigate molecular mechanisms underlying these effects. We found that two derivatives, eugenolol and glyceryl-isoeugenol, had potent inhibitory effects on LPS-induced upregulation of nitrite levels, iNOS protein and iNOS mRNA. In addition, they both suppressed the release of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) induced by LPS. Moreover, they both attenuated the DNA binding of NF-kB and AP-1, phosphorylation of inhibitory kB-alpha (IkB-alpha), and nuclear translocation of p65 protein induced by LPS. Finally, we demonstrated that glyceryl-isoeugenol suppressed the phosphorylation of ERK1/2, JNK and p38 MAPK, whereas eugenolol suppressed the phosphorylation of ERK1/2 and p38 MAPK. Taken together, these results suggest that that eugenolol and glyceryl-isoeugenol suppress LPS-induced iNOS expression by down-regulating NF-kB and AP-1 through inhibition of MAPKs and Akt/IkB-alpha signaling pathways. Thus, this study implies that eugenolol and glyceryl-isoeugenol may provide therapeutic benefits for inflammatory diseases.

Diabetes and coronary heart disease in American Indians: The Strong Heart Study.

Coronary heart disease (CHD) is the leading cause of death among American Indians. However, information on the prevalence of CHD and its association with known risk factors is limited. The purpose of the Strong Heart Study is to quantify CHD and its risk factors among three geographically diverse groups of American Indians. The population consists of 4,549 adults between 45 and 74 years of age in 13 Indian communities in Arizona, Oklahoma, and South and North Dakota. The phase I examination (1989-1991) revealed very high prevalence rates of diabetes that ranged from 33 to 72% in men and women in the three centers. Prevalence rates of definite myocardial infarction (MI) and definite CHD were higher in men than in women in all three centers (P < 0.0001) and in those with diabetes (P = 0.002 and P = 0.0003 in women and men respectively). Diabetes was associated with a relatively greater increase in prevalence of MI (prevalence rate = 3.8 vs. 1.9) and CHD (prevalence rate = 4.6 vs. 1.8) in women than in men. Logistic regression analysis indicated that the prevalence of CHD among American Indians was significantly related to age, diabetes, hypertension, albuminuria, percentage of body fat, smoking, high concentrations of plasma insulin, and low concentrations of HDL cholesterol. Lower prevalence rates of CHD were found in Arizona despite higher rates of diabetes, obesity, hypertension, and albuminuria; these lower rates may be in part related to lower smoking frequency and lower concentrations of total and LDL cholesterol. These findings from the baseline Strong Heart Study examination emphasize the relative importance of diabetes and its associated variables as risk factors for CHD among American Indian populations.

Dietary intakes of nutrients thought to modify cardiovascular risk from three groups of American Indians: The Strong Heart Dietary Study, Phase II.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of mortality among American Indians. Rates of CVD appear to be increasing among American Indians while they are decreasing among other racial and ethnic groups in the United States. Rates of comorbid conditions associated with CVD, such as obesity, impaired glucose tolerance, and hypertension, are also higher among American Indians than among other racial and ethnic groups in the United States. Dietary factors play a role in the development of CVD and associated comorbid conditions, yet surprisingly few data exist to describe the dietary intakes and nutritional adequacy of American Indian adults at risk for CVD. OBJECTIVE: To describe intakes of nutrients that may affect CVD risk consumed by members of 13 nations of American Indian adults, aged 45 to 70 years, who reside in tribal communities in Arizona, North Dakota, South Dakota, and Oklahoma. A secondary objective was to compare dietary intake estimates to nationally representative data from adults of similar age to determine potential dietary differences that may account for the disparities seen in rates of CVD and related conditions. Finally, dietary intake estimates were compared with national dietary guidance to determine areas for improvement. METHODS: Data from a 24-hour dietary recall provided by 3,482 adults who participated in the Strong Heart Dietary Study, Phase II, were analyzed to describe dietary intakes of nutrients that may alter CVD risk. Nonparametric analyses of variance were used to compare data by center, age, and sex. Dietary intake data for each sex/center group were compared with data from the Third National Health and Nutrition Examination Survey (NHANES III), Phase I, dietary estimates, and to national dietary guidelines. RESULTS: Nutrient intakes varied little between centers. Sex differences were noted in energy and nutrient intakes across all centers. Age-related decreases in energy and total and saturated fat intakes were noted among all sex/center groups. Median intakes of vitamins A and C and folate were low among all sex/center groups. Remarkably few differences in dietary intake were noted between NHANES III and Strong Heart Dietary Study, Phase II, participants. Carbohydrate and sodium intakes were higher among participants compared with NHANES III estimates, whereas intakes of several vitamins were lower. CONCLUSIONS: Dietary intakes of American Indians vary by age, sex, and geographic location, but do not differ substantially from national estimates of dietary intake. The dietary differences noted between NHANES III and Strong Heart Dietary Study, Phase II, participants are not consistent with the remarkably different rates of CVD and associated comorbidities that currently exist.

Hypertension in adult American Indians. The Strong Heart Study.

Hypertension is a primary risk factor for cardiovascular disease in the United States. Although cardiovascular disease is the leading cause of death among American Indians, the prevalence of hypertension, its awareness and control, and its association with other cardiovascular disease risk factors and physiological variables have not been well studied in this population. The Strong Heart Study is a longitudinal study of cardiovascular disease and its risk factors in American Indians. Participants (2703 women and 1846 men) were members of 13 tribes in central Arizona, southwestern Oklahoma, and regions of South and North Dakota. At least 1500 individuals between 45 and 74 years of age participated from each center in a baseline clinical examination conducted between July 1989 and January 1992. The examination consisted of a personal interview and physical examination that included an oral glucose tolerance test and three consecutive blood pressure measurements. This study reports data from the baseline examination on the prevalence of hypertension and correlates of blood pressure. Results indicated that despite the high frequency of diabetes and obesity, prevalence rates of hypertension in Arizona and Oklahoma were similar to those in the US population in the Third National Health and Nutrition Examination Survey (NHANES III), and rates among South/North Dakota participants were significantly lower (P < .0001). Blood pressure was higher in individuals with diabetes (P < .0001) and was significantly correlated with age (P < .0001) and albuminuria (P < .0001) but only weakly related to obesity. There was no independent relation between blood pressure and insulin. Blood pressure seems to be less affected by obesity and hyperinsulinemia in American Indians compared with other populations. Nevertheless, hypertension should be aggressively treated and controlled in American Indians because it is a known precursor to morbidity and mortality associated with diabetes and cardiovascular disease.

Guaiacoxypropanolamine derivatives of capsaicin: a new family of beta-adrenoceptor blockers with intrinsic cardiotonic properties.

A series of guaiacoxypropanolamine derivatives of capsaicin was synthesized by replacing the phenolic OH of N-nonanoylvanillamide with epichlorohydrin, followed by cleavaging the obtained epoxide compound with alkylamines. Intravenous injection of these propanolamine derivatives (1 mg/kg) in normotensive Wistar rats induced a transient fall in blood pressure but significantly reduced the heart rate for more than 30 min. These derivatives (10(-8)-10(-6) M) inhibited isoproterenol (10(-10)-10(-5) M)-induced positive chronotropic and inotropic effects in isolated guinea pig atrium. On the other hand, these derivatives (10(-5)-10(-4) M) exhibited a positive cardiotonic effect that is independent of intrinsic sympathomimetic effects. Investigation of the structure-activity relationship of these derivatives revealed that the position of the oxypropanolamine side chain and substituents of the 4-OH position play significant roles in imparting their pharmacological effects. Of the derivatives tested, the most effective one was compound 9. In conclusion, the results obtained from in vitro and in vivo studies suggested that these derivatives and compound 9 may be expected to be beta-adreneoceptor blocking agents with nonadrenergic positive chronotropic and inotropic properties.

Major electrocardiographic abnormalities among American Indians aged 45 to 74 years (the Strong Heart Study).

As part of the Strong Heart Study assessment of prevalent cardiovascular disease in middle-aged to elderly American Indians, the prevalence of major Minnesota code electrocardiographic (ECG) abnormalities was assessed in 4,531 participants aged 45 to 74 years (59% women) in selected tribal communities in Arizona, South and North Dakota, and Oklahoma. The overall prevalence of major ECG abnormalities was lowest in Arizona participants, (e.g., definite ECG myocardial infarction in 0.3% vs 1.8% in the other centers), although nearly two thirds of them had diabetes. One or more major ECG abnormality occurred in progressively more women (10.4% to 21.2%) and men (13.3% to 32%) (both p < 0.0001) from 45- to 54- to 55- to 64- and 65- to 74-year age groups, with the latter prevalence rates exceeding those in predominately white age peers in the Cardiovascular Health Study. Diabetes in women, but not in men, and hypertension in both genders showed positive associations with prevalence rates of major ECG abnormalities compatible with coronary artery disease or hypertensive cardiac hypertrophy. Hypercholesterolemia was not associated with ECG abnormalities except for definite myocardial infarction in women. In conclusion, major ECG abnormalities are common in middle-aged to elderly American Indians ,consistent with recent documentation of higher cardiovascular mortality in this population than in similar aged U.S. whites.

Capsinolol: the first beta-adrenoceptor blocker with an associated calcitonin gene-related peptide releasing activity in the heart.

1. The beta-adrenoceptor blocking and calcitonin gene-related peptide (CGRP)-releasing properties of capsinolol (N-[4-(2-hydroxy-3 (isopropylamino) propoxy)-3-methoxybenzyl]-nonanamide), derived from nonivamide, were investigated under in vivo and in vitro conditions. 2. Capsinolol (0.1, 0.5, 1.0 mg kg-1, i.v.), as well as (+/-)-propranolol, produced a dose-dependent bradycardia response and a temporary pressor action in urethane-anaesthetized normotensive Wistar rats. These cardiovascular effects were different from the vagus reflex and parasympathetic efferent effects shown by capsaicin (0.1 mg kg-1, i.v.) in the rat. 3. Capsinolol (1.0 mg kg-1) inhibited the tachycardia effects induced by (-)-isoprenaline, but had no blocking effect on the arterial pressor responses induced by (-)-phenylephrine. The findings suggest that capsinolol possesses beta-adrenoceptor blocking activity, but it has no alpha-adrenoceptor blocking activity. 4. In guinea-pig isolated tissues, capsinolol (10(-8) to 10(-6) M) antagonized (-)-isoprenaline-induced positive chronotropic and inotropic effects of the atria and tracheal relaxation responses in a concentration-dependent manner. The parallel shift to the right of the concentration-response curve of (-)-isoprenaline suggests capsinolol is a beta-adrenoceptor competitive antagonist. 5. Capsinolol (10(-5) to 10(-4) M) exhibited a positive cardiotonic effect that was not inhibited by (+/-)-propranolol and reserpine, but was inhibited by capsazepine (10(-6) M) and CGRP8-37 (10(-6) M). This effect was independent of intrinsic sympathomimetic effects. 6. An immunoassay of released CGRP from guinea-pig isolated perfused heart indicated that capsinolol increases the release of CGRP and thus produces positive cardiotonic effects. 7. In conclusion, capsinolol is a non-selective beta-adrenoceptor antagonist with capsaicin-like cardiotonic properties unrelated to traditional intrinsic sympathomimetic effects. It is suggested that capsinolol causes CGRP release from cardiac sensory neurones via a non-adrenergic mechanism and then activates CGRP receptors on cardiac muscle.

Hypertension treatment patterns in American Indians: the strong heart study.

Pharmacologic treatment patterns for hypertensive American Indians from 13 communities in Arizona, Oklahoma, South Dakota, and North Dakota were assessed. Participants (2254 women and 1384 men, aged 48 to 79 years) completed a clinical examination between July 1993 and December 1995. The mean of two blood pressure (BP) measurements and detailed medication histories were obtained. The observed prevalence of hypertension was 46.7% (n=1698). In participants taking antihypertensive medications (n=1114), four principal drug classes were evaluated: diuretics, calcium channel blocking agents, beta-blocking agents, and angiotensin-converting enzyme (ACE) inhibitors. Among treated hypertensive participants, 71.4%, 24.6%, and 4.0% received one, two, and three medications, respectively. Among single drug regimens, ACE inhibitors (n=340) were used most often (49.4%), with calcium channel blocking agents and diuretics accounting for 24.2% and 19.9%, respectively. Although multiple drug class therapies varied, the combination of a diuretic and ACE inhibitor (n=120) accounted for 47.4% of dual therapy use. Hypertension control (SBP < 140 mm Hg, DBP < 90 mm Hg) rates were highest for those on dual therapies (65.4%), followed by participants on single (53.8%) and triple (43.6%) therapies. Among monotherapies, diuretics exhibited the best overall hypertension control rate in both diabetics (63.0%) and nondiabetics (68.0%), versus 47% to 61% for other remaining agents. The frequent use of ACE inhibitors, used singly or in combination, reflects the high prevalence of diabetes among American Indians. ACE inhibitors, combined with diuretics, were particularly useful in achieving BP control in this population.

Nitric oxide is an autocrine feedback inhibitor of vascular smooth muscle contraction.

BACKGROUND: Substances that increase intracellular calcium ([Ca2+]i), such as potassium chloride and serotonin, are known to induce vascular smooth muscle (VSM) contraction. One form of nitric oxide synthase, which converts L-arginine to nitric oxide, exists as a Ca(2+)-calmodulin dependent enzyme. The objective of this study was to determine whether agonists that induce VSM contraction by increasing [Ca2+]i might also activate Ca(2+)-calmodulin dependent nitric oxide synthase in VSM. METHODS: Strips of bovine carotid arterial smooth muscle denuded of endothelium were equilibrated in a physiologic muscle bath. A maximal contractile response to high extracellular potassium chloride and serotonin was established. The strips were then preincubated with NG-monomethyl-L-arginine (L-NMMA), a structural analog of L-arginine and specific inhibitor of nitric oxide synthase, and again treated with either KCl or 5-hydroxytryptamine. RESULTS: The contractile responses of muscle strips to KCl or 5-hydroxytryptamine were significantly greater in muscle strips pretreated with L-NMMA than responses in the absence of L-NMMA (p < 0.02, Student's t test). To determine whether this response was Ca2+ dependent, phorbolester-induced contractions in Ca(2+)-free conditions were examined. No difference was noted in the magnitude of Ca(2+)-free, phorbol ester-induced contractions in the presence and absence of L-NMMA. CONCLUSIONS: These data thus suggest that Ca(2+)-calmodulin dependent nitric oxide synthase is functionally present in VSM and may function as an autocrine regulatory mechanism of VSM contraction.

Cardiovascular interactions of nonivamide, glyceryl nonivamide, capsaicin analogues, and substance P antagonist in rats.

Nonanoyl vanillylamide-4-o-glycerol (glyceryl nonivamide, GLNVA) a nonpungent ether-linked derivative of nonanoyl vanillylamide (nonivamide, NVA) was compared to capsaicin (CAP) and NVA with regard to its depressor response in rats. IV injection of CAP and NVA (10(-1) to 10(-4) mg/kg) in Wistar rats elicit a triphasic blood pressure response, bradycardia, and aponea. However, IV injection of GLNVA results in a monophasic reduction in blood pressure, with little effect on heart rate and respiration. The depressor response to GLNVA was not diminished by bilateral vagotomy or by systemic pretreatment with atropine. Following the CAP pretreatment, the delayed hypotension induced by CAP, NVA, and the hypotension of GLNVA was almost abolished. Injection of CAP, NVA (10 micrograms/kg), or GLNVA (100 micrograms/kg) into one femoral artery elicited a fall in blood pressure in the rat. This effect was abolished following intrathecal injection of substance P antagonist [D-Pro2,D-Trp7,9]-SP. Microejections of CAP, NVA, or GLNVA into the nucleus tractus solitarii (NTS) evoked hypotension, the bradycardia following microejection of CAP and NVA into the NTS occurred only at higher doses of GLNVA. From these results it is suggested that GLNVA appears to act more exclusively than CAP by stimulating peripheral perivascular small diameter C-fiber sensory nerves.

Autonomic and sensory cardiovascular activities of nonivamide: intrathecal administration of clonidine.

The effects of nonivamide on the cardiovascular system were examined and compared with the effects of substance P (SP) in rats. Intravenous (i.v.) injection (10 micrograms/kg) of nonivamide produced triphasic pressure responses (A; depressor, B; pressor, and C; depressor) and biphasic bradycardia responses (f; fast bradycardia and s; slow bradycardia). IA injection (10 micrograms/kg) into the epigastric artery caused hypotension and mild tachycardia. The effects of atropine, vagotomy, SP antagonist, propranolol, and clonidine on these responses were examined and mechanisms responsible for the nonivamide-induced responses are postulated as follows. A and f are due to vagal reflex resulting from the excitation of afferent sensory neurons in the heart and are parasympathetic efferent effects from the nucleus solitarius. B is involved in sympathetic activation, partly caused by the release of SP in the spinal cord. C is due to the vasodilatory effect of SP released from perivascular stores. s was diminished by vagotomy and is due to the bradycardiac effect of acetylcholine, released by SP, from cardiac stores. The activation of the autonomic system is inhibited by clonidine and involved in the wide spectrum of nonivamide-induced cardiovascular effects.

C-fiber-evoked autonomic cardiovascular effects after injection of Piper betle inflorescence extracts.

Piper betle inflorescence extracts contain eugenol (6.2%) and safrole (78.9%). Intravenous injections of water extracts of P. betle inflorescence (PBE), eugenol, and safrole in rats induced hypotensive and bradycardiac effects, whereas both intraarterial and intrathecal injections of PBE, eugenol and safrole resulted in hypotensive and tachycardiac effects. Moreover, the effects of intravenous injections of PBE were reversed or inhibited by the pretreatment with bilateral vagotomy, atropine (1 mg/kg, i.p.) and capsaicin (100 mg/kg, s.c.). Effects of intraarterial injections of PBE on blood pressure were inhibited by the pretreatment with substance P (SP) antagonist (1 nmol, i.t.) and clonidine (2.5 micrograms, i.t.), while heart rate was only inhibited by the pretreatment with SP antagonist (1 nmol, i.t.). In addition, the tachycardia resulting from intrathecal injections of PBE was inhibited by pretreatment with propranolol (0.3 mg/kg, i.v.). Eugenol and safrole induced the same pattern on blood pressure and heart rate changes as PBE in rats after various treatments. This report suggests that acute administration of betel inflorescence extracts by different routes may activate C-fiber-evoked parasympathetic and sympathetic cardiovascular reflexes in rats.

Role of Helicobacter pylori in cirrhotic patients with dyspepsia: a 13C-urea breath test study.

The role of Helicobacter pylori in dyspeptic, cirrhotic patients remains unclear. This prospective outpatient study, conducted to assess the relationship of gastroduodenal disease and H. pylori as determined by the (13C) urea breath test, enrolled 109 consecutive cirrhotic patients with dyspepsia. All patients underwent upper-gastrointestinal endoscopy, which revealed respective prevalences of peptic ulcer, gastric ulcer, and duodenal ulcer of 41.3%, 23.9%, and 22.9%; H. pylori infection was found in 52.3%. The rate of peptic ulcer disease in the H. pylori-positive (45.6%) and -negative (36.5%) groups was not significantly different; neither was the prevalence of H. pylori in patients with or without portal hypertensive gastropathy and with or without esophageal varices. The relationship between peptic ulcer disease and H. pylori in dyspeptic patients with cirrhosis appears to be weak. Likewise, no significant relationship was evident between H. pylori and portal hypertensive gastropathy or esophageal varices. This organism may not be a major pathogenetic factor in gastroduodenal diseases in dyspeptic patients with cirrhosis.

The interference of uptake of thallium-201 in cultured rat myocardial cells with existence of potassium related pharmaceuticals--a preliminary report.

Thallium-201 myocardial perfusion imaging is wildly used to detect and assess the extent of jeopardized myocardial ischemia in the coronary artery disease and the viability of myocardium post infarction. In recent years, there has been a great deal of pharmacological development of blockers and openers of potassium channel. In this study, we will discuss the interference of uptake of thallium-201 ion in cultured neonatal rat myocytes with existence of a variety of pharmacological agents. The cultures of neonatal rat myocardial cells were incubated with different agents such as potassium chloride, sodium-potassium ATPase pump inhibitor (ouabain), cesium compound, variable potassium channel blockers (4 AP, TEA and glibenclamide) and their openers (minoxidil, and cromakalim). The radioactivity of intracellular thallium-201 that could enter rat myocardial cells was detected by gamma counter sixty minutes after thallium-201 was added. In this study we found that thallium and potassium ions behave in an analogous manner in cultured rat myocardial cells. Both 2.5 mM and 5 mM concentration of extracellular potassium ion significantly result in reduction of thallium-201 ion influx in rat myocardial cells. 0.5 mM ouabain, an inhibitor of sodium-potassium ATPase pump, reduced about 40% of influx of thallium-201 ion in cultured rat myocardial cells via active transport. Combination of both potassium ion and ouabain inhibit most of thallium-201 ions influx in myocardial cells, but it is not completely inhibited. Cesium, a potassium antagonist, also interferes with the uptake of thallium-201 in cultured rat myocytes in our study. The most interesting finding in our investigation is that potassium channel blockers such as TEA and glibenclamide, inhibit the influx of thallium-201 in myocytes. However, potassium channel openers have no overt effect on influx of thallium-201 in cultured rat myocytes. We indirectly observe about 60% of influx of thallium-201 ion into cultured rat myocardial cells via active sodium-potassium ATPase pump. Potassium, cesium and potassium channel blockers, such as TEA and glibenclamide, inhibited the different percentage of influx of thallium-201 in cultured rat myocardial cells in this study.

Cardiovascular effects of nonivamide succinate.

Intravenous injection of nonivamide or nonivamide succinate (25, 250 nmol/kg) into Wistar rats induced bradycardia, hypotension, apnea and a triphasic blood pressure response: an initial short fall (effect A), an intermediate rise (effect B), and a subsequent delayed fall (effect C) of blood pressure. This blood pressure response remained unchanged after treatment with propranolol or phentolamine. In atropine-pretreatment rats the initial effect A was markedly decreased and effect C was slight increased. Effect A was absent after bilateral vagotomy. Unilateral microinjection of nonivamide succinate (3, 30 fmol) into the nucleus tractus solitarii produced a marked reduction in blood pressure and heart rate. In the isolated aorta of the guinea pig, application of either nonivamide or its succinate (10(-8) to 10(-5) M) eliminated the smooth muscle tone produced by phenylephrine (10(-6) M). Re-exposure to these agents, however, produced an immediate tachyphylactic relaxing response and prolonged rebound contractile response. Both compounds induced a vascular contraction rather than relaxation during tachyphylaxis. The potency of nonivamide succinate was found to be slightly greater than that of nonivamide.

Identification and characterization of a novel A-kinase-anchoring protein (AKAP120) from rabbit gastric parietal cells.

The type-II cAMP-dependent protein kinase (A-Kinase) partitions primarily into the particulate fraction in gastric parietal cells. Localization of this kinase to particular subcellular domains is mediated through the binding of the regulatory subunit (RII) dimer to A-Kinase-anchoring proteins (AKAPs). Using a [32P]RII overlay assay, we have screened a rabbit gastric parietal cell cDNA library and have isolated a single RII-binding protein clone. Sequence analysis revealed an open reading frame coding for 1022 amino acids (AKAP120). Recombinant fragments of the full-length clone were prepared and the RII-binding region mapped to an area between amino acids 489 and 549. This area contained a putative alpha-helical RII-binding region between amino acids 503 and 516. Incubation of [32P]RII with a synthetic peptide of AKAP120-(489-522) completely inhibited the binding of [32P]RII to the recombinant AKAP120 fragments that demonstrated RII binding. In vitro RII-binding affinity studies indicated a high-affinity interaction between AKAP120 and RII with a Kapp between 50 and 120 nM for the three recombinant fragments that bound [32P]RII. RNase-protection analysis revealed that AKAP120 is a widely distributed protein, with the highest levels of mRNA observed in gastric fundus. The presence of this novel high-affinity AKAP in gastric parietal cells suggests that it may regulate RII subcellular sequestration in this cell type.

Ionic effects of capsinolol, a calcitonin gene-related peptide releasing beta-adrenoceptor blocker, on isolated cardiac muscles.

1. Capsinolol (1.0-30.0 microM) in a cumulating manner decreased the maximum upstroke velocity (Vmax), the action potential amplitude and twitch tension in isolated guinea-pig atria and papillary muscle, rabbit papillary muscle, dog Purkinje fibers and human ventricle tissues. 2. In the isolated guinea-pig atrium, perfusing with capsinolol at 3 microM for 3 min temporarily increased the twitch force and decreased spontaneous cycle length; however, the results were reversed after longer exposure of the tissue. 3. Capsinolol prolonged the duration of action potential in the guinea-pig atrium and rabbit papillary muscles. The maximum diastolic potential was shifted to a less-negative level in dog Purkinje fibers and human ventricular muscles.

Vanidil: a newly synthesized antiangina nonvolatile organic solid nitrate.

Newly synthesized Vanidil (4-o-(1,2-dinitroglyceryl)-6-nitrovanillic acid) is a nonvolatile organic solid nitrate, mp: 85 degrees C. In in vitro tests, Vanidil can inhibit 3,4-diaminopyridine (2 x 10(-2) M) induced pig coronary rhythmic vasocontraction, a prelude to coronary vasospasm, and nonrhythmic tonic vasocontraction. Vanidil is suggested as a potential antiangina agent.

Capsazocaine: a capsaicin-sensitive functional antagonist displays an argument on sensory capsaicin receptor.

1. Intravenous infusion of capsazocaine (CAPBZ), a molecular fusion product of irritant synthetic capsaicin and local analgesic benzocaine, at 100 micrograms/kg/min for 15 min inhibited capsaicin (10 micrograms/kg, IV)-induced spinal release of substance P-like immunoreactivity and vagus reflex responses in blood pressure and heart rate changes in rats. 2. Intrathecal perfusion of CAPBZ (1.0 nM) also reversed retrograde epigastric intraarterial capsaicin (10 micrograms/kg)-induced hypotensive spinal reflex. 3. In isolated guinea pig tissues, CAPBZ (1.0-100.0 microM) inhibited capsaicin (1.0 microM)-sensitive sensory and functional activities, including cardiatonic, bronchial, tracheal and ileal contractilities. CAPBZ is suggested to be a capsaicin antagonist.