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

Studies of myocardial utilization of fatty acids and analogs has focused on coronary heart disease. This study addresses the topic of radioiodinated fatty acid utilization in hypertensive-cardiomyopathy. The new fatty acid analog 19-iodo-3,3-dimethyl-18 nonadecenoic acid (DMIVN) was studied by autoradiographic microimaging (ARG) in salt-sensitive (S) hypertensive (salt-fed) and in salt-sensitive (S) normotensive (low-salt diet), Dahl-strain rats. A salt fed, S-strain group was treated with verapamil and the results were compared to those in a hypertensive, non-treated group. The distribution of DMIVN in the hearts of normotensive rats was uniform. In the myocardium of hypertensive rats nonuniform DMIVN concentration was seen in the subendocardial and mid-layers of the left ventricle (LV). Verapamil given to salt-fed rats prevented hypertension and uniform DMIVN uptake similar to normotensive controls was seen. The data suggest that DMIVN may be suitable for the detection of hypertension induced myocardial changes and for assessing therapy. The distribution and clearance characteristics of DMIVN indicate that DMIVN may be a useful agent for SPECT imaging in man.
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PMID:Studies of a new fatty acid analog (DMIVN) in hypertensive rats and the effect of verapamil using ARG microimaging. 280 54

Experiments were conducted on five chronically instrumented unanesthetized sheep to determine the effects of verapamil, a calcium channel inhibitor, on the pulmonary hemodynamic and microvascular permeability responses to endotoxemia. Paired control endotoxemia experiments (E) and endotoxemia with verapamil treatment (30-60 micrograms.kg-1.min-1) experiments (V + E) were conducted on each sheep in random order. In the V + E experiments sheep were pretreated with a continuous intravenous infusion of verapamil 1.5-2.0 h before endotoxin infusion (1.0 microgram/kg, given over 15 min). Verapamil significantly increased base-line pulmonary arterial pressure, left atrial pressure, lung lymph flow rate, and circulating blood leukocyte levels and significantly decreased base-line cardiac output. During the endotoxin response, verapamil significantly attenuated both phase I pulmonary arterial hypertension and phase II lung lymph flow rate compared with control endotoxin experiments. The results indicate that verapamil attenuates both the pulmonary hemodynamic and increased lung microvascular permeability response to endotoxin in sheep. In a series of in vitro experiments, verapamil was found to be a potent inhibitor of phorbol myristate acetate-induced superoxide production in isolated sheep granulocytes. These data suggest that the beneficial in vivo effects of verapamil during endotoxemia may in part be due to its inhibition of increased free cytosol calcium concentration and/or inhibition of toxic O2 metabolite production.
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PMID:Verapamil attenuates lung vascular responses to endotoxin in sheep. 285 Feb 94

1. Calcium antagonists, including verapamil, are now used widely in the management of patients with hypertension. 2. Six weeks of chronic therapy with verapamil (50 mg/kg per day, orally) to produce a plasma level of 80-100 ng/ml in Sprague-Dawley rats depletes cardiac noradrenaline (NA) without apparently causing beta 1 adrenoceptor 'up' regulation. 3. The effect of verapamil on cardiac NA is rapidly reversed upon verapamil withdrawal. 4. Chronic therapy with nisoldipine (100 mg/kg per day, orally) had no effect on cardiac NA. 5. Verapamil (50 mg/kg per day, orally) and nisoldipine (100 mg/kg per day, orally) therapy for 6 weeks prevented the time-dependent increase in systolic blood pressure in SHR rats. 6. Binding studies with (-)[3H]-D888 (desmethoxyverapamil) indicated that the affinity of the phenylalkylamine binding sites is higher in hearts of SHR relative to hearts from age-matched (25 weeks) WKY and SD, without any change in density.
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PMID:Calcium antagonists and hypertension. 285 52

The demonstration that antihypertensive drug treatment reduces mortality and morbidity in persons with mild hypertension has extended the indications for treatment. Verapamil, nitrendipine, angiotensin converting enzyme inhibitors and beta-adrenoceptor blocking drugs are equally effective in reducing blood pressure. The choice of which drug to use depends on the presence or absence of specific contraindications and the occurrence of adverse effects in the individual patient.
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PMID:Comparison of calcium antagonists with other antihypertensive agents. 286 75

The antianginal and antiarrhythmic role of calcium antagonists is well established. Recent preliminary studies have indicated that, like beta blockers, calcium antagonists may produce short- and long-term hypotensive effects in patients with mild to moderate essential hypertension. The pharmacologic properties of calcium antagonists provide a clear rationale for their use in the control of essential hypertension. The comparative hypotensive effects of verapamil (80 to 160 mg 3 times a day) and propranolol (40 to 120 mg 3 times a day) were evaluated over 4 weeks, preceded by a 4-week placebo phase, in a double-blind protocol in 17 patients with mild to moderate hypertension. Verapamil (n = 10) reduced the mean sitting systolic blood pressure by 10.7% (p less than 0.01) and standing by 7.6% (p less than 0.04). The corresponding data for propranolol (n = 7) were 4.8% (not significant) and 5% (p = 0.04). Verapamil reduced the sitting diastolic blood pressure by 10.8% (p less than 0.01), propranolol by 7.5% (p = 0.01); the standing diastolic blood pressure was reduced by 10.7% with verapamil (p less than 0.01) and by 8.6% (p = 0.01) with propranolol. With verapamil the mean heart rate fell from 77.60 +/- 8.42 to 70.20 +/- 4.85 beats/min (p = 0.03); with propranolol it fell from 76.85 +/- 6.91 to 66.29 +/- 4.54 beats/min (p less than 0.01). Although a trend towards a slightly greater hypotensive effect was apparent with verapamil compared with propranolol, the difference was not statistically significant. It is concluded that verapamil and propranolol exert comparable hypotensive potency in patients with mild to moderate hypertension.
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PMID:Calcium antagonists and beta blockers in the control of mild to moderate systemic hypertension, with particular reference to verapamil and propranolol. 286 76

Calcium antagonists are a chemically heterogenous group of agents with potent cardiovascular effects which are beneficial in the treatment of angina pectoris, arterial hypertension and cardiac arrhythmias. The main side effects for the group are dose-dependent and the result of the main action or actions of the calcium antagonists, i.e. vasodilatation, negative inotropic effects and antiarrhythmic effects. Pronounced hypotension is reported for the main calcium antagonist drugs; verapamil, diltiazem and nifedipine. While conduction disturbances and bradycardia are seen more often after verapamil and diltiazem, tachycardia, headache and flush are more frequent after nifedipine. Constipation is relatively frequent after verapamil while nifedipine is reported to induce diarrhea in som patients. Idiosyncratic side effects are rare but have been reported from the skin, mouth, musculoskeletal system, the liver and the central nervous system. These side effects include urticarial rashes, gingival hyperplasia, arthralgia, hepathotoxicity and transistory mental confusion or akathisia. Verapamil, diltiazem and possibly also nifedipine have been reported to increase serum digoxin concentrations but the clinical relevance of these drug interactions are not clear. Furthermore, verapamil and diltiazem may potentiate the effects of beta-adrenergic blocking drugs and verapamil may also potentiate the effects of neuromuscular blocking drugs. It is concluded that side effects after calcium antagonist drugs are mostly trivial and transient although they may sometimes be relatively common. Clinically relevant drug interactions are few. Judged from the point of efficacy and safety, calcium antagonists will have a major place in the future pharmacotherapy of several cardiovascular disorders.
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PMID:Calcium channel blockers: spectrum of side effects and drug interactions. 287 68

Verapamil and nifedipine enhance the hypotensive and anti-anginal effects of beta-adrenoceptor blocking drugs. The combination of beta-adrenoceptor blocking drugs with nifedipine may pose fewer safety problems than the combination with verapamil especially in ischaemic heart disease when left ventricular function is suspect. Verapamil as a single agent may be as effective as a beta-adrenoceptor blocking drug in angina and provide a suitable alternative. Careful supervision is required when verapamil is combined with beta-adrenoceptor blockers for both angina and hypertension but reported clinical problems in hypertension are few.
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PMID:Combination therapy with beta-adrenoceptor blockers and calcium antagonists. 287 27

The effects of the calcium antagonists verapamil and nifedipine on mean arterial blood pressure, heart rate and pressor responses to a range of alpha-adrenoceptor agonists were examined in male normotensive New Zealand white rabbits and in rabbits with perinephritis hypertension. Verapamil and nifedipine caused a greater fall in mean arterial pressure in hypertensive compared to normotensive rabbits both when the fall was expressed as an absolute and as a percentage change. Effects on heart rate were similar in normotensive and hypertensive animals. Pressor responses to phenylephrine were attenuated by nifedipine and verapamil in normotensive and hypertensive rabbits. Pressor responses to alphamethyl noradrenaline were also attenuated by nifedipine, but pressor responses to BHT 920 were not significantly altered by either calcium antagonist in normotensive or hypertensive rabbits at the dose used. Thus the calcium antagonists had a greater effect on alpha 1 - than alpha 2-adrenoceptor mediated responses in both normotensive and hypertensive rabbits. Hypertensive animals showed an increased responsiveness to phenylephrine and alphamethyl noradrenaline but not BHT 920 compared to normotensives. This difference remained after treatment with both the calcium antagonists.
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PMID:The effects of calcium antagonists on blood pressure and responses to alpha-adrenoceptor agonists in hypertensive rabbits. 288 40

We evaluated the response to salt restriction in hypertensive patients receiving drugs. By restricting their salt intake to less than 80 mmol of sodium per day for 3 months, 50% of patients reaching goal compliance were able to discontinue diuretics. The literature also reveals responses to a low salt diet. Salt restriction augmented the hypotensive effect of chlorthalidone in two investigations, but not in another, and the hypotensive effect of beta-blockers in three trials. Sodium intake of 10 mmol/day caused a much greater decrease in blood pressure in response to a single dose of captopril than did a sodium diet of 200 mmol/day. In patients receiving various fixed regimens for 2 months, salt restriction decreased blood pressure in all but those receiving calcium blockers. A single dose of nifedipine lowered blood pressure more in patients receiving 350 mmol of sodium per day than in the same patients given 150 or 10 mmol/day. Verapamil for 3 days was more effective in patients receiving 212 mmol of sodium per day than in the same subjects receiving 9 mmol/day. Nitrendipine caused a greater decrease in diastolic blood pressure in patients who did not reduce salt intake compared to those who did. Salt restriction appears useful in salt-sensitive patients who receive beta-blockers, diuretics, converting enzyme inhibitors, or centrally acting drugs. Calcium channel entry blockers may not require salt restriction to maximize their effect.
Hypertension 1988 Feb
PMID:Review of salt restriction and the response to antihypertensive drugs. Satellite symposium on calcium antagonists. 289 58

The demonstration that antihypertensive drug treatment reduces mortality and morbidity in mild hypertension has extended the indications for treatment. Verapamil, nitrendipine, angiotensin converting enzyme inhibitors and beta-adrenoceptor blocking drugs are all equally effective in reducing blood pressure. The choice of drug depends on the presence or absence of specific contra-indications and the occurrence of side effects in individual patients.
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PMID:Comparison of calcium antagonists with other antihypertensive agents. 290 21


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