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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of the selective 5-HT2 agonist (+-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane HCl (DOI) on arterial pressure (AP), heart rate (HR), renal blood flow (RBF) and plasma renin activity (PRA) was determined in conscious rats. DOI increased AP and PRA, but decreased HR and RBF. All responses to DOI were abolished by central (LY 53857) or peripheral (xylamidine) 5-HT2 antagonists. Prazosin did not alter the AP or HR response to DOI. Chlorisondamine abolished the bradycardia but slightly increased the hypertension produced by DOI, while enalapril attenuated the pressor response. No further reduction was produced by the combination of enalapril and prazosin. Propranolol attenuated but did not eliminate the renin response, and blocked the bradycardia elicited by DOI. The data suggest that DOI activates 5-HT2 receptors located on vascular smooth muscle and/or the circumventricular organs of the brain to: (1) increase AP and reflexly decrease HR, (2) decrease RBF and (3) increase PRA. The hypertension is mediated by angiotensin II and direct vascular effects whereas the increase in PRA is mediated by an interaction of increased sympathetic nerve activity and decreased renal perfusion pressure.
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PMID:Hemodynamic and renin responses to (+-)-DOI, a selective 5-HT2 receptor agonist, in conscious rats. 218 26

These studies were undertaken to examine the contribution of central nervous system mechanisms to the cardiovascular and sympathoadrenal effects of cocaine. Changes in systolic and diastolic blood pressure, heart rate and plasma catecholamine concentrations were determined in response to cocaine injected i.a. or i.c.v. in conscious unrestrained rats. Systemically administered cocaine produced brisk, transient dose-related increases in systolic and diastolic pressure at doses of 0.05 to 5 mg/kg i.a. Plasma catecholamine concentrations increased in a dose-related manner, reaching peak levels at 5 to 10 min after i.a. cocaine injection. Only the higher doses of cocaine induced reflex vagal bradycardia that was blocked by atropine (0.4 mg/kg i.a.). Propranolol (1 mg/kg i.a.) prolonged the duration of cocaine-induced hypertension and bradycardia. Ganglionic blockade with chlorisondamine (7.5 mg/kg i.a.) antagonized completely the cardiovascular and sympathoadrenal effects of cocaine, indicating that intact ganglionic transmission is required for full expression of the autonomic responses. Antagonist drugs selective for the D-1 or D-2 dopamine receptors attenuated effects of cocaine on plasma catecholamine concentrations but not on cardiovascular parameters. Intracerebroventricular injection of cocaine (50-250 micrograms) increased systolic pressure and plasma catecholamine concentrations, providing direct evidence for an action of cocaine in the central nervous system. These results demonstrate that cocaine acts centrally to increase sympathetic outflow leading to hypertension and reflex bradycardia in conscious rats.
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PMID:Role of the central nervous system in hemodynamic and sympathoadrenal responses to cocaine in rats. 221 51

The powdered bark of Maquira sclerophylla is consumed as snuff in north Brazil. Both the crude and the purified hydrosoluble extract (WP) injected i.p. in the dose range of 0.05-0.5 g/kg induced hyperexcitability, tremors, motor incoordination, ataxia, quietness and muscle relaxation in rats. The effects were progressive, dose-related and reversed after 30 min. Anesthetized rats, guinea-pigs and dogs injected with the purified extract (10-50 mg/kg, i.v.) showed a biphasic change of carotid blood pressure. The early and transient hypotension was blocked by atropine but not by vagotomy: the secondary hypertension was long lasting and sustained for over 30 min. The hypertension was shortened but not blocked after ganglionic blockade or reserpine treatment. Either pithing or alpha receptor blockade with yohimbine reduced both effects of the extract. Guinea-pigs and dogs were more responsive than rats and died by heart arrest. Incubation of WP (20 micrograms/ml) increased both the rate and force of contraction of isolated guinea-pig right atria by 2 and 5 times, respectively. Propranolol (4 micrograms/ml) blocked the chronotropic effect but did not decrease the inotropic effect. In electrically driven guinea-pig left atria, WP (10 micrograms/ml) increased the force of contraction by 80% and the maximum rate of force development by 60%, but did not change the time to peak tension, the time to 50% relaxation, or the rate of relaxation. These cardiovascular effects resemble those of digitalis-like drugs. Cardenolides were detected in WP by phytochemical screening.
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PMID:Pharmacology of an Indian-snuff obtained from Amazonian Maquira sclerophylla. 221 23

This was a prospective, randomized, double-blind, placebo-controlled trial to establish whether beta blockers or calcium-channel blockers limit exercise capacity and training responses in men with mild hypertension. Circuit weight and aerobic training was used to assess the effects of drugs on cardiovascular fitness and muscle strength. Fifty-two sedentary men, ages 25-59 yr, with a diastolic blood pressure of 90-105 mm Hg off drugs, without significant ST depression during maximal stress testing, received diltiazem, propranolol, or placebo. Maximal oxygen uptake (VO2max) and exercise duration during treadmill testing, as well as one-repetition maximal strength, were assessed on eight weight machines after a single-blind placebo baseline, after 2 wk of drug run-in, and after 10 wk of exercise training. Total daily doses were 240 mg for propranolol and 360 mg for diltiazem. Propranolol decreased VO2max after drug run-in (P less than 0.05). Exercise training increased VO2max (P less than 0.05) in the diltiazem and placebo groups. After training VO2max in the propranolol group increased (P less than 0.05) from run-in but not beyond baseline levels. Thus, the reduction of VO2max consequent to propranolol therapy limited the overall benefits of training. Exercise duration did not change with run-in and increased (P less than 0.05) with training by 22%, 19%, and 10% for the diltiazem, placebo, and propranolol groups, respectively. Strength after run-in was unchanged, and exercise training increased strength (P less than 0.0001) on all weight machines in all groups. The results show an advantage of diltiazem to propranolol, particularly among physically active patients engaged in aerobic exercise who require antihypertensive therapy.
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PMID:Effects of diltiazem or propranolol during exercise training of hypertensive men. 235 13

To investigate the mechanisms of action of nicotine we studied the effect of muscarinic and adrenergic receptor antagonists on nicotine-induced changes in the lungs and circulation. Nicotine increased mucus secretion from tracheal submucosal glands and caused bronchocon-striction. Cardiovascular effects were a bradycardia followed by tachycardia, hypertension and a biphasic increase in cardiac output. All of these effects were completely blocked by prior administration of hexamethonium. Propranolol and phentolamine prevented the increase in heart rate, and reduced the increase in blood pressure. Only atropine inhibited nicotine-induced hypersecretion and bronchocon-striction.
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PMID:[Effect of repeated nicotine administration on mucus secretion, bronchodilation and circulatory variables: inhibitory effect of autonomic antagonists]. 236 68

The forearm arterial effects of enalapril and propranolol were compared by means of pulsed Doppler velocimetry in 28 patients with hypertension after treatment for 3-6 months. Enalapril decreased blood pressure, increased both brachial artery diameter and blood flow, decreased vascular resistance, and increased the arterial compliance of the forearm. Propranolol also decreased blood pressure but did not produce any other changes. It may be concluded that the treatment of hypertension with enalapril, but not propranolol, is associated with dilatation effects on the arterial circulation of the forearm.
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PMID:Effects of chronic administration of enalapril and propranolol on the large arteries in essential hypertension. 241 92

The present study examined the actions of dilevalol, an antihypertensive beta-adrenoceptor blocker with arterial vasodilator actions, upon aortic compliance (AC) in anesthetized dogs. AC was determined via sonomicrometric determination of the ratio of aortic systolic-diastolic diameters (mm) and arterial pulse pressure (mm Hg). One AC unit (ACU) equals 10(-3) mm/mm Hg. Dilevalol (0.032, 0.1, and 3.2 mg/kg i.v.) significantly (p less than 0.05) increased AC by 1.4 +/- 0.3, 3.7 +/- 1.4, and 4.5 +/- 1.2 ACU, respectively, from basal values of 4.7 +/- 0.4-5.6 +/- 0.4 ACU, while reducing blood pressure by 20 +/- 2, 31 +/- 9, and 41 +/- 10 mm Hg, respectively (p less than 0.05). Increases in AC were not the passive result of altered blood pressure. Proximal mechanical aortic occlusion dropped systolic blood pressure as much as 70 mm Hg without altering AC. Propranolol (0.32 and 1.0 mg/kg) did not significantly change AC, but propranolol pretreatment attentuated dilevalol-induced increases in AC. Pindolol (0.1-1.0 mg/kg i.v.) lowered blood pressure 17 +/- 3 (p less than 0.05) to 34 +/- 7 mm Hg (p less than 0.05), while significantly increasing AC by 1.2 +/- .2 to 2.7 +/- .7 ACU. The data show that dilevalol, unlike propranolol, increases AC substantially at antihypertensive doses. The inhibition of dilevalol-induced AC increases by propranolol illustrates a beta-adrenoceptor agonist activity in large arteries. Since large artery compliance is impaired in hypertension, dilevalol may afford a vasular protective action for known risk factors for evolving systemic arterial disease.
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PMID:Effects of the antihypertensive dilevalol on large artery compliance in anesthetized dogs. 245 69

A multicenter, randomized, double-blind, comparative study was conducted in 274 patients with mild to moderate hypertension to assess the impact of nitrendipine and propranolol on quality of life. After placebo baseline, 136 patients were given nitrendipine (5-20 mg b.i.d.) and 138 were given propranolol (40-120 mg b.i.d.). Quality of life was evaluated at baseline, weeks 6-10, and weeks 14-18 of the maintenance period. At weeks 6-10, the nitrendipine group became significantly more vigorous (p less than 0.01) and less fatigued (p less than 0.05) than the propranolol group. Propranolol subjects noted decreased problems of trembling hands (p less than 0.01) and alcohol use (p less than 0.05) than the nitrendipine subjects. No other significant differences between groups in mood states, troublesome conditions (insomnia, headaches, and loss of appetite), or sexual satisfaction were noted at this visit, and patient willingness to continue study medication was marginally significantly higher (p less than 0.1) in the nitrendipine group than in the propranolol group. At weeks 14-18, the propranolol subjects perceived significantly decreased problems with the "felt worried, tense, and drank alcohol to cope" factor (p less than 0.05); however, there were no differences between groups at this visit for Profile of Mood States (POMS) scores, sex life variables, or medication preference. Based on within-group analysis, the propranolol group perceived a reduction in partner sexual satisfaction (p less than 0.05). Overall, nitrendipine seemed to be better tolerated than propranolol.
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PMID:Comparison of quality of life on nitrendipine and propranolol. 246 71

The aim of this study was to compare the effects of long-term monotherapy with five different beta-blockers on plasma lipids in patients with essential hypertension. We studied 99 male patients, aged 35-55 years, with mild to moderate hypertension, who worked in the same community. After a 1-month placebo period, patients were assigned to receive propranolol (160 mg/day), atenolol (100 mg/day), bisoprolol (10 mg/day), mepindolol (10 mg/day), or celiprolol (400 mg/day). Therapy was continued for 2 years. Blood pressure (BP), heart rate, and blood samples for evaluation of total cholesterol (TC), LDL-cholesterol (LDL-C), triglycerides (TG) and HDL-cholesterol (HDL-C) were taken before and after the initial placebo period, and subsequently every 6 months from the beginning of active treatment. All beta-blockers caused similar reductions in BP that were maintained throughout the study. None of the beta-blockers significantly affected TC or LDL-C. Propranolol, a nonselective beta-blocker, caused the most pronounced changes in TG (+33 to 43%) and in HDL-C (-30 to -32%). Atenolol, a beta 1-selective agent, had the same quantitative effects, but to a lesser extent (TG + 23 to 30%; HDL-C -15 to -19%). Bisoprolol, more beta 1-selective than atenolol, and mepindolol, nonselective with ISA, increased TG (+20 to 28% and +14 to 25%, respectively) but did not significantly affect HDL-C. In contrast, celiprolol, a highly cardioselective beta-blocker with beta 2-partial agonism, improved lipid risk factors by significantly reducing TG (-14 to -21%) and increasing HDL-C (+8 to 14%).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Plasma lipids during chronic antihypertensive therapy with different beta-blockers. 248 87

1. Six healthy subjects received cilazapril (2.5 mg once daily), propranolol (120 mg once daily), the combination of both and placebo for a period of 1 week each (wash-out phase 1 week). 2. Propranolol and cilazapril reduced systolic and diastolic blood pressure (BP) by 7 mm Hg at peak when compared with placebo. However after the combination, this reduction was more than doubled (18 mm Hg) and lasted longer. 3. There was a trend to lower and later peak concentrations for both drugs after administration of the combination. No clinically relevant pharmacokinetic interactions between cilazapril and propranolol were found. 4. The effects on blood pressure were confirmed in hypertensive patients (BP diastolic greater than 95 mm Hg). Thirteen patients were randomly allocated cilazapril (2.5 mg day-1) or propranolol (120 mg day-1] as part of a cross-over design. This was then followed by the combination. All treatment periods were of 3 weeks duration and all measurements were done 2 h after drug administration. 5. Cilazapril lowered the median sitting diastolic BP by 8 mm Hg, and propranolol by 9 mm Hg, whereas the combination reduced the diastolic BP by 19 mm Hg. 6. The results of these studies, attempting to elucidate drug-drug interactions, showed that combined use of propranolol and cilazapril resulted in a more pronounced and longer lasting blood pressure reduction, in healthy subjects and in patients with hypertension.
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PMID:Pharmacokinetic and pharmacodynamic interactions between the ACE inhibitor cilazapril and beta-adrenoceptor antagonist propranolol in healthy subjects and in hypertensive patients. 252 45


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