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

Labile hypertension is often associated with elevated cardiac output, increased plasma renin activity (PRA) and urinary cyclic AMP excretion in response to upright posture and to isoproterenol. The beta-blocking agent propranolol was demonstrated to be an effective therapeutic agent in this condition. The effect of posture on cyclic AMP, PRA, pulse rate and blood pressure was therefore studied during the administration of propranolol and a placebo in patients with labile hypertension. With the patient on placebo, upright posture induced an increase in pulse rate, cyclic AMP excretion and PRA. Propranolol administration decreased the recumbent and upright blood pressures, pulse rate and PRA. Cyclic AMP excretion remained unchanged in the recumbent position but the postural increase was abolished. No appreciable changes in catecholamine excretion occurred during propranolol administration. Propranolol normalizes some humoral as well as hemodynamic abnormalities of labile hypertension and therefore may be of benefit in long-term treatment and possibly also in the prevention of stable hypertension.
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PMID:Effect of propranolol on cyclic AMP excretion and plasma renin activity in labile essentrial hypertension. 435 22

In a previous study we observed an increase in urinary cyclic AMP in labile hypertension in the upright position and during isoproterenol infusion, in contrast to a decrease in control subjects. In the present study we measured the plasma level of cyclic AMP in control subjects and patients with various types of hypertension. We obtained the following results: (1) plasma cyclic AMP increases in response to upright posture in control subjects and hypertensive patients; (2) values of cyclic AMP in the recumbent and upright positions are comparable in control subjects and patients with essential hypertension, but are significantly higher in those with true renovascular hypertension due to bilateral renal artery stenosis; (3) propranolol inhibits the increase of plasma cyclic AMP in response to posture in control subjects, but has an opposite effect in labile hypertension where there is a further increase; (4) the rise in blood pressure in pheochromocytoma is associated with a considerable increase in plasma cyclic AMP.Present and previous data suggest that kidney handling of cyclic AMP is abnormal in hypertension, and that the specific defect may be related to the type of hypertension.
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PMID:Plasma adenosine 3',5'-cyclic monophosphate in human hypertension. 436 18

Beta-endorphin and related opioid peptides are neuropeptides which appear to play a role in cardiovascular regulation which is supported by altered nociceptive responsiveness in hypertensive animals. In spontaneously hypertensive rats the pain threshold for electric stimulation is elevated; these rats show increased response latency time in a hot plate test. The opiate antagonist naloxone reverses these values to that of the normotensive controls. In other forms of experimental hypertension, eg, renal hypertension (one-clip, two-kidney model), no change in pain sensitivity is apparent. Sinoaortic baroreceptor denervation causes a labile hypertension without changes in hot plate response. Administration of beta-endorphin into the nucleus of the solitary tract (NTS) gradually decreases blood pressure and heart rate without affecting respiratory frequency. These cardiovascular effects are blocked by naloxone as well as by an antibody to beta-endorphin. In contrast to the effects of beta-endorphin, microinjection of enkephalins into the NTS increases blood pressure and heart rate. The data suggest the existence of two separate endorphin systems at the level of the NTS, one a depressor and another a pressor system. The depressor influence of beta-endorphin may play a role in the mechanism of action of antihypertensive agents such as methyldopa and clonidine. Our data support a role of endorphins as neuropeptides involved in cardiovascular regulation, exerting a dual influence at the level of the NTS.
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PMID:Role of opioid peptides in brain mechanisms regulating blood pressure. 629 7

A case of 49-year-old Japanese house wife with a functioning parathyroid carcinoma was reported. Because of lack of bone and renal involvements, she was classified as chemical type of primary hyperparathyroidism. Abnormally high levels of serum calcium and a small palpable tumor on the right anterior neck had suspected a functioning parathyroid carcinoma, which was proved histologically after operation. Preoperatively, she had a labile hypertension (116-190/68-126 mmHg) with high plasma renin activity (PRA; 2.3-8.4 ng/ml/h). The marked responses of PRA to furosemide and captopril were accompanied by inappropriate low response of aldosterone. After removal of the tumor, her blood pressure returned to normal with lowered PRA and normal serum calcium. These observations strongly suggested that her elevated PRA might be a main role to yield hypertension.
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PMID:A case of functioning parathyroid carcinoma with hypereninemic hypertension. 634 70

The drug albetol (labetalol) was used in 97 patients with stage I-III essential hypertension (according to the WHO classification) and 13 patients with stable arterial hypertension of renal genesis. Albetol exerted a marked hypotensive effect beginning from the 2-3d day of the treatment and peaking on the 6-8th day of the treatment. To normalize the blood pressure, the patients with labile hypertension were given the drug in a dose of 200-400 mg/day whilst in the patients with a stable course the dose used was 600-2200 mg/day (858 mg/day on the average). In patients with the hyperkinetic type of the hemodynamics the blood pressure decreased following albetol administration at the expense of a reduction in the cardiac index and the heart rate whereas in patients with the hypokinetic type it was achieved mostly at the expense of a decreased vascular resistance to the blood flow. The drug was effective in 69% of the patients, it was well tolerated and induced no side effects.
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PMID:[Use of Albetol for treating hypertension patients]. 639 71

The plasma renin activity (PRA), plasma volume (PV), urinary excretion of Kallikrein (UK) and PGE2, PGF2 alpha, 6-keto PGF1 alpha and TXB2 were measured in 24 ambulant patients without treatment on normal sodium diets with pregnancy-induced hypertension (HT) (diastolic BP greater than or equal to 90 mmHg, appearing after 20 weeks' pregnancy and absent 2 months after delivery). The UK was measured by an esterase technique, prostaglandins by radioimmunological assay and PV by dye dilution (Evans blue). Two subgroups of patients were identified according to the evolution of their blood pressure at rest at home; the first (7 patients) with labile HT, and the second (14 patients) with permanent HT. The PRA was significantly lower (p less than 0,001) in patients with permanent compared to labile hypertension (4,7 +/- 0,3 compared to 12,2 +/- 0,8 ng/ml/h) and compared to a control group of normotensive pregnant women (6,5 +/- 0,5). The PV, expressed as a percentage of the theoretical volume with respect to the stage of pregnancy and body surface area was low in both groups. In permanent HT: 1) there was no correlation between PV and PRA, 2) a positive correlation between UK and urinary 6-keto PGF1 alpha (r = 0,62; p less than 0,001) and PGE2 (r = -0,51, p less than 0,05). Discriminative linear analysis showed that urinary 6-keto PGF1 alpha was mainly related to PRA and to a lesser degree to UK.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Renin-angiotensin-aldosterone system, blood volume, serum uric acid and urinary excretion of prostaglandins and kallikrein in the arterial hypertension induced by pregnancy]. 644 41

Systolic time interval (STI) analysis is a commonly employed noninvasive technique for evaluating myocardial function. It requires simultaneous recording of an electrocardiogram, phonocardiogram, and the carotid pulse contour, from which left ventricular ejection time is measured. The carotid pulse contour may be difficult to record when there is subject movement, such as with exercise or other stresses utilized in aerospace medical research. Impedance cardiography is a relatively new noninvasive technique for measuring stroke volume. It also provides a measure of systolic ejection time without the necessity of recording a carotid pulse contour. The purpose of this study was to determine the correlation between left ventricular ejection time (LVET) determined from conventional STI analysis and systolic ejection time (T) obtained with impedance cardiography. The electrocardiogram, phonocardiogram, carotid pulse contour, and impedance cardiogram were monitored simultaneously in 17 male subjects 39-63 years of age (6 normotensive, 7 with established hypertension, and 4 with labile hypertension). Subjects were monitored at seated rest and during submaximal and maximal cycle ergometer exercise. Beat-by-beat analysis revealed high intrasubject correlations between LVET and T for each subject during all three activity levels. Correlations between LVET and T for the combined group of 17 subjects were: rest r = 0.990, submaximal exercise r = 0.976, maximal exercise r = 0.986; p less than 0.01. These results indicate impedance cardiography can be used in the determination of STIs for the evaluation of ventricular function, as well as for the noninvasive determination of stroke volume and cardiac output.
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PMID:Correlations between ejection times measured from the carotid pulse contour and the impedance cardiogram. 665 10

Four cases of intracerebral hemorrhage remote from the site of the initial neurosurgical procedure are presented. Two of the four patients had preoperative hypertension. Possible mechanisms are discussed, and labile hypertension and unstable blood pressure during the perisurgical period may be contributory. Clinical awareness of this rare but potential complication is essential to early diagnosis and treatment. Difficulty in awakening from anesthesia and the development of new neurological deficits not attributable to the operative site are the most important keys to early diagnosis. Computed tomography is the diagnostic method of choice.
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PMID:Intracerebral hemorrhage remote from the site of the initial neurosurgical procedure. 665 20

There is some evidence that atherosclerosis and hypertension can already start in childhood or adolescence. For early detection in this age group, therefore regular blood pressure readings should be routine. Blood pressure in American and German children and adolescents is rising with age, in boys more than in girls; this phenomenon is not so striking in the Yanomamo-Indians. The frequency of hypertension in population studies of children and adolescents (systolic blood pressure above 139 mm Hg, diastolic blood pressure above 89 mm Hg) is 1-2% (fixed hypertension) vs. about 10% (labile hypertension).
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PMID:[Epidemiology of hypertension in childhood]. 666 51

Central hemodynamic changes were investigated in 88 patients with essential hypertension after 5-year supervision. With adequate treatment the circulation type common to a given form of hypertension was basically preserved so that no hemodynamic changes were noted. The natural course of the disease was associated with considerably increased total peripheral resistance, while eu- and hypokinetic, instead of hyperkinetic, circulation gradually began to prevail in patients with labile hypertension. Plasma renin activity and renal cortical blood flow decreased. These changes are conducive to the stabilization and progress of arterial hypertension.
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PMID:[Prospective evaluation of hemodynamic changes in patients with hypertension]. 666 87


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