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

The Wistar rat, with a blood pressure range of 120-160 mmHg, and two strains of spontaneously hypertensive rats (SHR), stroke-prone (SHRSP, range 210-270 mmHg) and stroke-resistant (SHRSR, range 160-240 mmHg), were used to determine the degree of damage after ischemic insult induced by bilateral carotid artery ligation (BLCL). The survival rate and McGraw Stroke Index correlated well with the degree of hypertension. After BLCL, impairment of cerebral blood flow is abrupt and residual flow is near zero in rats with initial blood pressures greater than 200 mmHg. A markedly deteriorated aerobic metabolism, as measured by the concentrations of ATP, c-AMP and lactate, is seen to precipitate in rats with initial blood pressures greater than 180 mmHg and severe edema occurs if the pressure is more than 160 mmHg. The degree of hypertension that produces high vulnerability to stroke and severe damage to the brain after ischemic insult is indicated as beginning at about 180 mmHg.
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PMID:Susceptibility to ischemic insult in hypertensive rats: correlation between degree of ischemia and hypertension. 301 58

The effects of the rapid infusion of large doses of dibutyryl cyclic AMP (DBcAMP) were studied to clarify the clinical usefulness of its vasodilating action in 32 middle-aged patients, who underwent various types of surgery and developed systolic hypertension of over 160 mmHg during general anaesthesia. DBcAMP was given i.v. with an infusion pump at a rate of 0.6 mg kg-1 min-1 for 20 min. In all patients just after the infusion, systolic arterial pressure decreased from 174.0 +/- 20.7 to 129.0 +/- 23.9 mmHg, diastolic pressure decreased from 93.1 +/- 13.4 to 64.8 +/- 13.3 mmHg, heart rate increased from 81.2 +/- 15.7 to 91.5 +/- 19.5 beats min-1, and urine volume increased from 69.4 +/- 54.8 to 182.7 +/- 143.5 ml h-1. In three patients, cardiac index increased from 3.44 to 4.24 l min-1 m-2. In seven patients, tachycardia exceeding 120 beats min-1 developed. DBcAMP was also effective in patients with a history of hypertension. The strongest antihypertensive effect was observed in patients anaesthetized with nitrous oxide-oxygen and enflurane. We speculate that DBcAMP is useful to control hypertension and may be particularly indicated in patients with cardiac failure, renal disorders and essential hypertension.
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PMID:The control of hypertension with dibutyryl cyclic AMP. 303 96

beta-Adrenoceptor agonists and other drugs were studied for their relaxant effects on femoral and mesenteric arterial strips from spontaneously hypertensive rats (SHR). The potency and efficacy of isoproterenol (ISO) in these arteries were decreased in SHR before and during the development of hypertension as compared with age-matched Wistar Kyoto rats (WKY). Reserpine and 6-hydroxydopamine inhibited the development of hypertension but did not alter the reduced ISO-induced relaxation of the arteries. These arteries from prehypertensive SHR (PHSHR) were less sensitive to salbutamol and cyclic AMP and cyclic GMP derivatives than arteries from age-matched WKY. The relaxation response to nitroprusside was less in the femoral but not in the mesenteric arteries from PHSHR than in arteries from age-matched WKY. The relaxation response to papaverine was not diminished in the PHSHR arteries. It was found that the SHR arteries had a reduced responsiveness to the beta-adrenoceptor agonists before the initiation of hypertension and that the diminished relaxation was not specific to the beta-agonists, although there was no generalized defect in vasorelaxation in PHSHR.
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PMID:Diminished beta-adrenoceptor-mediated relaxation of arteries from spontaneously hypertensive rats before and during development of hypertension. 303 46

We report the clinical and biological picture of 34 primary hyperparathyroidism (PHT) cases, diagnosed in rheumatology. It concerned 25 women and 9 men, aged 61 + 11 years. The PHT was often asymptomatic (47 p. cent of cases) at the time of diagnosis. The clinical manifestations were dominated by asthenia (50 p. cent) and renal lithiasis (47 p. cent). We found a chondrocalcinosis in 29 p. cent of patients. No patient presented any bony manifestations of cystic osteitis; 7 out of 34 patients (including 6 women between 57 and 74 years) presented vertebral compression. The mean calcemia was 117 +/- 9 mg/l. There were no hypercalcemic attack. The dosage of PTH and cyclic AMP were elevated in 29 out of 32 and 28 out of 31 patients respectively. In all patients, the level of either of these two tests was increased. The chloremia/phosphoremia ratio was also extremely predictive of HBP, since it was increased, exceeding 3.3 in 33 out of 34 patients. The 25-hydroxyvitamin D levels (25 (OH) D) were normal. The levels of 1,25 (OH) 2D were markedly spread (37 +/- 16 pg/ml) and not significantly different from the reference group. Patients with lithiasis did not present a higher level of 1,25 (OH) 2D. A bone histomorphometry carried out in 15 patients showed a bone trabecular volume similar to that of the reference with the same age. The osteoclastic resorption was increased in all cases and was not correlated with the PTH level, but was significantly correlated with the level of 1,25 (OH) 2D (r = 0.79 p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Primary hyperparathyroidism seen in rheumatology. Clinical symptoms and the relation between bone histologic signs and biological parameters]. 326 11

A symposium of over 125 scientists, held in August 1984 at the campus of Oxford University, considered the latest developments concerning cannabis research. Evidence on the mode of tetrahydrocannabinol action on the central nervous system indicates that acetylcholine turnover in the hippocampus through a GABA-ergic mechanism is of major importance, though the role of the dopaminergic or serotoninergic mechanism and involvement of prostaglandins and c-AMP is not ruled out. The use of cannabis causes prominent and predictable effects on the heart, including increased work-load, increased plasma volume and postural hypotension, which could impose threats to the cannabis users with hypertension, cerebrovascular disease or coronary arteriosclerosis. Cannabis or tetrahydrocannabinol has damaging effects on the endocrine functions in both male and female of all animal species tested. Among possible mechanisms of action, it is suggested that tetrahydrocannabinol disrupts gonadal functions by depriving the testicular cells of their energy reserves by inhibition of cellular energetics, and that it stimulates androgen-binding protein secretion, which may account for oligospermia seen in chronic cannabis smokers. In addition to these direct effects on gonads, tetrahydrocannabinol interferes with hormonal secretions from the pituitary, including luteinizing hormones, follicle-stimulating hormones and prolactin. Research findings indicate that maternal and paternal exposure to cannabinoids can influence developmental and reproductive functions in the offspring, but it is difficult to separate possible teratogenic effects from subsequent gametotoxic and mutagenic potentials of cannabinoids.
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PMID:An update on cannabis research. 391 16

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

An acute hot stress caused a sharp increase in plasma cyclic AMP and cyclic GMP in both spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). This hot stress-induced increase in plasma cyclic AMP was observed even after chemical sympathectomy elicited by 6-hydroxydopamine or depleting the catecholamine stores in adrenergic neurons by tyramine or reserpinization, but was no longer observable after beta-adrenergic blockade by propranolol, blockade of autonomic ganglia by hexamethonium, adrenodemedullation or anesthesia by pentobarbital. These results indicate that the initial stimulation of the central nervous system evoked the release of catecholamines from the adrenal medulla which could activate adenylate cyclase via the stimulation of beta-adrenoceptors on the cell surface. The increment of plasma cyclic GMP was not influenced by prior blockade of the peripheral autonomic nervous system, but was totally abolished by pentobarbital, indicating that cyclic GMP generated within the central nervous system in response to the hot stress would be directly related to its increase in the peripheral blood stream. The plasma cyclic AMP and cyclic GMP responses were greater in adult SHR than in young SHR and young and matured WKY. The predominant response of plasma cyclic AMP might be due to a greater release of catecholamine from the adrenal medulla in matured SHR. The hyperresponse of plasma cyclic GMP in adult SHR remains to be fully elucidated. The increased cyclic nucleotide responses in SHR might be an important factor in the maintenance of hypertension.
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PMID:Plasma cyclic nucleotides in spontaneously hypertensive rats: hyperresponse to acute hot stress. 608 98

Alpha-adrenergic receptor function was measured in platelets from patients with orthostatic hypotension and normotensive controls. Patients with idiopathic orthostatic hypotension (IOH) or multiple system atrophy (MSA) had more alpha-receptors than controls. Patients with IOH, but not MSA, produced less prostaglandin E1 (PGE1)-stimulated cyclic AMP (cAMP) than controls. Patients with sympathotonic orthostatic hypotension (SOH) were similar to controls in receptor number and cAMP production. The percent norepinephrine (NE) inhibition of PGE1-stimulated cAMP production was similar in patients and controls. An increase in alpha-receptor number may result from decreased peripheral NE secretion in IOH and MSA. Increased alpha-receptor number and decreased cAMP production, which accompany essential hypertension, may contribute to the supine hypertension of IOH, and an increase in alpha-receptor number may contribute to the supine hypertension of MSA. SOH patients appear to have no abnormalities of alpha-receptor function.
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PMID:Alpha-adrenergic receptors in orthostatic hypotension syndromes. 608 6

Three different pressure groups of rats, stroke-prone spontaneously hypertensive rats (SHRSP, 200-270 mmHg), stroke-resistant SHR (SHRSR, 160-240 mmHg), and Wistar rats (WR, 120-160 mmHg) were used to investigate the effect of prior existing hypertension on the severity of brain damage induced by ischemia. The cerebral ischemia was induced by bilateral common carotid artery ligation (BLCL) and the survival rate, cerebral blood flow, cerebral energy metabolites (ATP, lactate c-AMP) and water content were measured. Colloidal carbon perfusion was also performed. Sixteen-week-old male rats were used. The survival rate was observed until 24 hours after BLCL. Cerebral blood flow was measured in parietal cortex by hydrogen clearance method. ATP was measured by luciferin-luciferase method, and lactate by enzymatic method using LDH. c-AMP was measured by radioimmunoassay. Brain water content was measured by freeze-dry method. These measurements were done for animals surviving 6 hours of BLCL. Colloidal carbon perfusion was done according to Ames' Method. The survival rate was lower in the hypertension group. The survival of SHRSP and SHRSR were 20% compared to 71% in WR after 24 hours of BLCL. The cerebral circulation of SHRSP fell abruptly and was near to zero after one hour of BLCL. In SHRSR this fall of cerebral blood flow was prominent in the rats of higher blood pressure. On the other hand there was no apparent fall of cerebral blood flow in WR after BLCL. The cerebral energy metabolites. ATP and c-AMP showed the lowest level in SHRSP which had the negative correlation to blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Experimental cerebral ischemia after bilateral common carotid artery ligation in SHRSP, SHRSR and Wistar rats: correlation between blood pressure and degree of ischemia]. 609 92


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