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

Cytosolic free calcium concentrations determine the magnitude of tension development of smooth muscle cells and are pivotal for regulation of vascular smooth muscle tone and systemic vascular resistance. Elevated free calcium concentrations have been found in platelets from hypertensive patients, and platelet free calcium concentration, possibly an index of vascular smooth muscle cell free calcium concentration, correlated with blood pressure in normotensive and hypertensive subjects. Increased systemic vascular resistance in essential hypertension depends on increased calcium influx. Calcium antagonists lower cytosolic free calcium concentrations mainly through a reduction of transmembraneous calcium influx and are potent arterial vasodilators. High blood pressure is lowered through a reduction of elevated systemic vascular resistance but, in contrast to other direct acting vasodilators, without clinically relevant sympathetic reflex activation. However, subtle changes of sympathetic nervous system activity may codetermine the acute and chronic blood pressure response. Calcium antagonists do not lead to volume retention, because of improved intrarenal hemodynamics and a diuretic effect. Interference with angiotensin and sympathetically mediated vasoconstrictor mechanisms probably also contributes to their antihypertensive effects. This favorable hemodynamic profile renders calcium antagonists suitable for monotherapy of uncomplicated hypertension where they are particularly effective in older patients and also for the therapy of hypertensive crisis.
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PMID:Mechanisms of action of calcium antagonists in hypertension. 245 34

The effect of aerobic exercise on cardiac arrhythmias, plasma catecholamines, potassium and magnesium in patients with systemic hypertension was assessed. Twenty patients (age 54 +/- 8 years) with uncomplicated hypertension underwent exercise treadmill testing twice while receiving placebo and twice while receiving hydrochlorothiazide 100 mg daily. Blood samples for electrolytes and catecholamines were obtained at rest, at peak exercise and 10 minutes after exercise. There were no substantial differences comparing the first to the second placebo phase or the first to the second treatment period. As expected, hydrochlorothiazide treatment caused a significant decrease in serum potassium (4.00 +/- 0.44 to 3.32 +/- 0.49 mEq/liter, p less than 0.001). Serum magnesium did not change with treatment. Serum potassium, serum magnesium and plasma catecholamines increased significantly with exercise. No rebound hypokalemia occurred during recovery. Occasional ventricular premature contractions were noted at rest during all phases of the study, with only a slight increase in frequency during exercise. Couplets were noted only rarely. No difference in the frequency or complexity of arrhythmias was noted between placebo and treatment periods. Diuretic therapy or diuretic-induced hypokalemia has no profound effect on cardiac arrhythmias during or after exercise in patients with uncomplicated systemic hypertension.
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PMID:Effects of diuretic therapy and exercise-related arrhythmias in systemic hypertension. 247 52

To evaluate determinants of elevated plasma atrial natriuretic factor levels in patients with hypertension, immunoreactive plasma atrial natriuretic factor in 54 normal subjects and 40 untreated hypertensive patients was compared with echocardiographic measurements of cardiac size, function and systemic hemodynamics. In normal subjects, plasma atrial natriuretic factor was related to age, systolic blood pressure and left atrial and ventricular chamber sizes, but only age and ventricular size were independent predictors. In untreated hypertensive patients, atrial natriuretic factor was directly related to age, atrial size, systolic pressure, peripheral resistance and ventricular systolic performance; age, atrial size and peripheral resistance were independent predictors. Eight patients with elevated atrial natriuretic factor values (greater than 25 fmol/ml) were significantly (p less than 0.01) older and had greater atrial and ventricular size and higher systolic pressure and function than normal subjects or patients with normal natriuretic factor levels. Plasma atrial natriuretic factor was inversely related to peak diastolic filling rate in normal subjects (r = -0.59; p less than 0.001), whereas it was positively related to the proportional contribution of atrial systole to left ventricular filling in hypertensive patients (r = 0.77; p less than 0.001). These findings suggest that in normal subjects, impairment of ventricular relaxation with age may contribute to atrial natriuretic factor secretion by increasing left atrial afterload; the correlation with left ventricular size may reflect physiologic fluctuations in plasma volume. In patients with uncomplicated hypertension, left atrial enlargement and consequent stronger atrial contraction contributed to increased atrial natriuretic factor release, whereas no independent relation existed with left ventricular hypertrophy or systolic function. Because ventricular relaxation was normal and ventricular size and systolic performance were increased in hypertensive patients with high atrial natriuretic factor levels, the observed increase in left atrial size and atrial contribution to ventricular filling might reflect a primary increase in venous return in this subset of hypertensive patients.
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PMID:Plasma atrial natriuretic factor in essential hypertension: relation to cardiac size, function and systemic hemodynamics. 252 1

Calcium antagonists are potent arterial vasodilators that do not lead to relevant chronic sympathetic reflex activation and sodium and volume retention. This favorable hemodynamic profile renders them suitable for monotherapy of hypertension in which they can reduce the calcium influx-dependent functional component of elevated vascular resistance that may be enhanced by altered vascular muscle cation handling and increased intracellular free calcium concentrations. Clinical studies have proved their efficacy, safety, and good tolerability alone or in combination with other drugs in uncomplicated hypertension in which they are particularly effective in older, low renin, and possibly, black patients. These properties and their efficacy in the treatment of severe and accelerated hypertension or hypertensive emergencies make them a valuable addition to already available drug therapy.
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PMID:Mechanisms of action and clinical use of calcium antagonists in hypertension. 255 76

1. The interaction of ouabain, a Na+/K+ adenosine 5'-triphosphatase inhibitor, with sympathetic mechanisms of vasoconstriction, as well as its possible site(s) of action, were investigated in forearm arterioles of patients with uncomplicated hypertension. 2. Intra-arterial infusion of ouabain per se decreased forearm blood flow without changes in systemic arterial pressure or contralateral flow. However, the vasoconstrictor effect of the glycoside was abolished after local pretreatment with either phentolamine, a competitive alpha-adrenoceptor antagonist, or bretylium tosylate, a neurotransmitter blocker. 3. To exclude a non-specific effect due to the vasodilatation, a similar protocol was performed using histamine, which acts independently of sympathetic mechanisms. The vascular effect of ouabain was maintained in spite of histamine-induced increases in forearm blood flow even greater than those obtained from either blocker. 4. To discriminate between pre- and post-synaptic site(s) of action of ouabain, exogenous noradrenaline was infused intra-arterially after inactivation of local neurotransmitter release by bretylium, thus causing direct postsynaptic vascular alpha-adrenoceptor stimulation. Under these conditions, noradrenaline decreased forearm blood flow irrespective of the presence or absence of ouabain. 5. Thus, local sympatholysis by drugs acting on different levels of the sympathetic neuroeffector junction abolished the effect of ouabain, whereas histamine did not influence it. The data provide positive evidence for an effect of ouabain on sympathetically mediated vasoconstriction. This action is apparently not exerted at a postsynaptic site but possibly by enhancing neurotransmitter release. 6. If a circulating endogenous ouabain-like Na+/K+ adenosine 5'-triphosphatase inhibitor is relevant to the development of hypertension in man, it might act through a similar mechanism.
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PMID:Sympathetic vasoconstriction as a mechanism of action of ouabain in forearm arterioles of hypertensive patients. 258 25

Seventeen patients with hypertension and osteoarthritis participated in a single-blind crossover study comparing the effects of sulindac 200 mg twice daily, naproxen 500 mg twice daily, and placebo on blood pressure. All patients were treated for hypertension with propranolol monotherapy. Blood pressures were back-titrated to achieve a baseline diastolic blood pressure of 90 to 100 mm Hg while taking naproxen. There were no significant differences in mean sitting or standing blood pressures among the patients receiving naproxen, sulindac, or placebo treatments. There was no change in pulse, weight, or any of the laboratory measurements at the end of each treatment phase. These results suggest that neither sulindac nor naproxen interferes with propranolol therapy for uncomplicated hypertension.
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PMID:Lack of interaction between sulindac or naproxen and propranolol in hypertensive patients. 266 52

Previous studies carried out on the treatment of hypertension in the elderly patient indicate that, in this group of patients, antihypertensive treatment can reduce cardiovascular mortality mainly by reducing mortality from cerebrovascular diseases. To date, the success of hypertensive treatment in over-80-year-olds with uncomplicated hypertension, and patients with isolated systolic hypertension, has not been documented. In the treatment of the elderly patient, age-specific pathophysiological changes need to be taken into account. Such changes are deteriorating renal performance, increased vasoconstriction, decreasing baroreceptor function, declining cardiac performance, and changes in the autoregulation of cerebral blood flow. For this reason, in geriatric hypertensives, the blood pressure should be reduced gradually over a period of weeks. Antihypertensive drugs with a natriuretic or vasodilative effect are pathophysiologically meaningful, while substances that result in a loss of potassium, depression of the sympathetic nervous system and negative inotropism are not so favorable.
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PMID:[Treatment of hypertension in the aged]. 268 41

Twenty-five patients below the age of 40 years with Uncomplicated hypertension underwent selective renal arteriography to assess the involvement of interlobar and arcuate arteries. Renal vasculature was abnormal in all 25 patients. Patients with severe hypertension had markedly abnormal renal vasculature. None of the patients with mild hypertension had severe vascular involvement. Functional significance of these arteriographic abnormalities is discussed.
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PMID:An arteriographic assessment of renal vasculature in young patients with essential hypertension. 273 84

Sixty patients were treated for 1 year for essential uncomplicated hypertension, 30 with beta-blockers alone (BB) and 30 with BB and chlorthalidone (CTD). BB did not affect serum K+ or Mg++. In the BB-group there was a statistically significant trend towards retention of Mg++ in a loading test, but the effect was clinically marginal. BB + CTD reduced serum K+ and Mg++ and caused significant Mg++ depletion, as shown by the Mg++ loading test. All the effects were highly significant and were clinically important. The metabolic perturbations due to CTD are potentially dangerous and make this drug unattractive as 'first choice' treatment for hypertension.
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PMID:Magnesium depletion in patients on long-term chlorthalidone therapy for essential hypertension. 288 40

To evaluate the performance of M-mode echocardiography for detection of pressure-overload left ventricular hypertrophy (LVH), we tested the sensitivity of previously defined sex-specific upper limits of normal echo LV measurements in 31 patients with necropsy-proven pressure-overload LVH and determined the prevalence of LVH detected by each echo criterion in 316 employed patients with uncomplicated hypertension, 100 patients with hypertension evaluated in a referral center, and 38 hospital patients with moderate to severe (WHO class 2) hypertension. Echo measurements were LV mass (LVM), LVM index (LVMI), cross-sectional area (CSA), septal and posterior wall thickness (IVST and PWT), LV internal dimension (LVID), and relative wall thickness (RWT). Prevalences of echo LVH were as follows. (Table: see text). Thus, echo criteria based on LVM are more sensitive than other measurements for detection of necropsy-proven pressure-overload LVH and reveal the highest prevalence of LVH in clinical hypertension populations, and the prevalence of LVH in hypertension is highly dependent on the population studied.
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PMID:Echocardiographic detection of pressure-overload left ventricular hypertrophy: effect of criteria and patient population. 295 68


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