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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 insulin-induced hypoglycemia on the blood levels of catecholamines and renin activity has been studied in five patients with moderate hypertension before and after treatment for 3 - 8 months with penbutolol (PEN) 20 - 30 mg twice daily. Penbutolol caused no change in fasting blood glucose level. Insulin o.1 IU per kg body weight i.v. reduced blood glucose concentration by approximately 50 per cent after 30 - 45 min, both before and during treatment with penbutolol. Hypoglycemia prior to medication was accompanied by a marked increase in the production of adrenaline and a minor increase of noradrenaline in all five patients. During treatment the response of adrenaline to hypoglycemia was reduced in four patients and the data was inconclusive in one. Basal renin activity was rather low in three patients, within the normal range in one and relatively high in one. Before penbutolol the hypoglycemia-induced increase in catecholamine production caused no change in plasma renin activity in the three patients with low basal levels, whereas a marked increase was observed in the other two. During medication plasma renin activity remained unchanged on induction of hypoglycemia regardless of the catecholamine response. Despite the marked increase in plasma adrenaline following insulin-induced hypoglycemia, no statistically significant increase in pulse rate was recorded.
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PMID:Long term treatment of moderate hypertension with penbutolol (Hoe 893d). II. Effect on the response of plasma catecholamines and plasma renin activity to insulin-induced hypoglycemia. 0 1

The cardiovascular effects of hypoglycaemia, with and without beta-blockade, were compared in fourteen healthy men. Eight received insulin alone, and eight, including two of the original insulin-only group, were given propranolol and insulin. In the insulin-group the period of hypoglycaemia was associated with an increase in heart-rate and a fall in diastolic blood-pressure. In the propranolol-insulin group there was a significant fall in heart-rate in most subjects and an increase in diastolic pressure. Typical S-T/T changes occurred in the insulin-group but in none of the propranolol-insulin group. Hypertension in diabetics prone to hypoglycaemia attacks should not be treated with beta-blockers because these drugs may cause a sharp rise in blood-pressure in such patients.
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PMID:Modification by propranolol of cardiovascular effects of induced hypoglycaemia. 4 35

The sympathetic nervous system is of major importance for the regulation of several physiological functions. Drugs which inhibit the actions of catecholamines and adrenergic drugs are used in the treatment of many clinical disorders. The potential role of catecholamines in a number of human diseases has, however, until recent years been studied to a limited extent only due to lack of methods for quantitation of sympathetic nervous activity. After the development of enzymatic isotope-derivative assays, reliable measurements of noradrenaline and adrenaline in plasma became available. Studies in man have shown that plasma noradrenaline is an index of sympathetic nervous activity. The present survey deals with sympathetic nervous activity and plasma adrenaline in a number of clinical disorders viz. arterial hypertension, duodenal ulcer, thyrotoxicosis, diabetes mellitus and ketotic hypoglycemia.
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PMID:The role of catecholamines in clinical medicine. 10 29

Insulin-induced hypoglycemia previously has been shown to provoke a beta-adrenergic response that normally results in an increase in plasma renin activity (PRA). In our study, hypoglycemia induced definite increases in PRA in a group of five patients with normal renin essential hypertension but failed to do so in a group of six patients with low renin essential hypertension. In both groups, plasma cyclic adenosine 3',5'-monophosphate (cyclic AMP; cAMP) increased more than 2-fold during hypoglycemia, but the response in the low renin group was significantly less than that previously observed in normal subjects under the same conditions. Plasma cortisol increased to an equal extent in both groups of hypertensive patients during hypoglycemia. Infusion of the phosphodiesterase inhibitor, theophylline, resulted in definite increases of PRA in patients with normal renin hypertension but not in patients with low renin hypertension. Because changes in the level of plasma cAMP during hypoglycemia have been thought to reflect adrenal catecholamine release, our finding of a blunted increase in plasma cAMP during hypoglycemia in patients with low renin hypertension may suggest that there is a generalized alteration in adrenergic responsiveness in this condition.
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PMID:Contrasting effects of hypoglycemia on plasma renin activity and cyclic adenosine 3',5'-monophosphate (cyclic AMP) in low renin and normal renin essential hypertension. 17 76

The diagnosis of florid Cushing's syndrome is usually made without difficulty but diagnostic problems may arise. Five such cases are described. Difficulties may occur when the features of the syndrome are incomplete. Three such cases were encountered. In each only one clinical feature was present; these respectively were hypertension, osteoporosis and obesity. The diagnosis was confirmed, however, biochemically and eventually histologically and there was a good response to surgery in each case. Another diagnostic problem, both clinically and biochemically is the obese, hirsute, hypertensive female. Two such cases are described, in whom Cushing's syndrome was diagnosed clinically and biochemically but in whom there was no response to adrenalectomy. Retrospectively the validity of the original diagnosis is questioned. It is concluded that Cushing's syndrome may present in a very incomplete form and should be considered in the differential diagnosis, even if only one feature is present. It is stressed that obesity, hirsutism, hypertension and depression are commonly found in association with normal adrenal function. Urinary free cortisol and cortisol response to insulin induced hypoglycaemia may be of value in distinguishing these cases from those with endocrine disease.
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PMID:Problems in the diagnosis of Cushing's syndrome. 19 80

In various kinds of hypertension clonidine induced a decrease in urinary catecholamines, plasma renin activity and urinary aldosterone, concommitant with a fall in blood pressure and pulse rate in both short term and chronic studies. Furthermore, clonidine lowered the plasma levels of noradrenaline and adrenaline but a postural increase in upright position still occurred. The capacity to increase renin during salt restriction seemed mainatined. When clonidine was withdrawn all parameters returned to pretreatment levels but in some cases a marked rebound increase in catecholamine production was seen. --During clonidine the increase in catecholamines and renin after insulin induced hypoglycemia was largely abolished. Under basal conditions oral penbutolol induced a decrease of pule rate and blood pressure but no change in plasma or urinary catecholamines. During treatment plasma renin was suppressed at rest and after exercise. A work load, which led to only minor changes in blood catecholamines before treatment, was associated with a marked increase during penbutolol. Medication with penbutolol reduced the response in plasma catecholamines after hypoglycemia and renin activity remained low. Clonidine seems to act mainly by central inhibtion of symapthetic tone. Penbutolol probably acts mainly peripherally but may also have a central effect.
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PMID:The effect of clonidine and penbutolol, respectively on catecholamines in blood and urine, plasma renin activity and urinary aldosterone in hypertensive patients. 23 81

1. An earlier study had demonstrated that indomethacin, administered before E. coli endotoxin, abolished the initial pulmonary vasoconstriction and delayed the onset of the secondary shock phase that results from the intravenous injection of this agent in cats. The object of the present study was to determine whether indomethacin modified the shock phase when administered after endotoxin. 2. All the cats (whether or not they received indomethacin, 10 mg/kg) exhibited the characteristic features of the delayed shock phase that result from the administration of endotoxin (2 mg/kg). These included systemic hypotension, hypoglycaemia, reductions in arterial pH, cardiac output and systolic ejection time and an increase in arterial lactate. Five out of the ten animals given indomethacin survived 4 h compared with four out of twelve in the control (endotoxin along) group. 3. These results do not support the suggestion that antipyretic-analgesic drugs like indomethacin may be of benefit when given during bacteraemic or septic shock. They do support the suggestion that the acute pulmonary changes (hypertension and decreased compliance) that occur in this species within a few minutes of endotin administration ultimately contribute to the severity of the shock phase.
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PMID:E. coli endotoxin shock in the cat; treatment with indomethacin. 23 1

Six normal subjects and six normotensive insulin-dependent diabetics underwent two insulin hypoglycaemia tests after administration for three days of either a placebo or of acebutolol--a cardioselective beta-blocker--at a dose of 400 mg per day. The order in which the tests were performed was decided by random selection. Acebutolol suppressed the tachycardia which occurred as a reaction to hypoglycaemia but did not interfere with other warning symptoms and signs. In both normal subjects and diabetics, acebutolol neither worsened the initial hypoglycaemia nor did it delay a return to normal values. The increase in lactate levels following hypoglycaemia was not reduced by acebutolol but free fatty acid rebound was suppressed. Hormonal responses (glucagon, cortisol, growth hormone) were unaffected by the beta-blocker. If they are confirmed by long term studies, these results would suggest that acebutolol is safer to use than non-cardioselective beta-blockers in the treatment of coronary insufficiency and of hypertension in diabetics exposed to the risk of hypoglycaemia.
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PMID:[The effects of acebutolol on endocrine and metabolic reactions induced by acute hypoglycaemia. Study in normal subjects and in insulin-dependent diabetics (author's transl)]. 39 44

What regulates the activity of the central nervous renin-angiotensin system is not known. To define whether control of this central system is linked to that in the periphery, simultaneous blood and cerebrospinal fluid (CSF) samples for measurement of immunoreactive angiotensin II were drawn from anesthetized dogs during hemorrhage, furosemide-induced volume depletion, insulin-hypoglycemia, beta-adrenergic blockade and saline infusion. Despite vigorous increments or decrements in plasma innunoreactive angiotensin II, CSF levels remained stable. Since immunoreactive angiotensin II in dog CSF is claimed to be mainly the heptapeptide des-Asp1-angiotensin II (angiotensin III), the possibility that the level of this peptide within CSF simply reflects plasma concentrations was assessed by infusing angiotensin III (2.5 and 25 ng/kg/min intravenously, each for 60 minutes) and monitoring plasma and CSF peptide levels. Whereas plasma immunoreactive angiotensin II levels increased appropriately across the infusions, no change in CSF levels was observed. These studies indicate the angiotensin III does not cross the blood-CSF barrier, at least in the short term.
Hypertension
PMID:Independence of the central nervous and the peripheral renin-angiotensin systems in the dog. 39 35

The role of physiological changes occurring during prolonged seizures in the causation of epileptic brain damage has been investigated experimentally in baboons and rats. Prolonged drug-induced myoclonic seizure activity is associated with initial arterial hypertension and subsequent hypotension, increased venous pressure, early hyperglycaemia and subsequent hypoglycaemia, variable arterial hypoxia and lactacidosis, and hyperpyrexia. Cerebral metabolic rate for oxygen and glucose is increased 2--3 fold throughout prolonged seizures provided the physiological status of the animal is well maintained. Ischaemic neuronal change is found after seizures lasting 1.5--7 hours, involving the small neurones of the third cortical lamina, Purkinje and basket cells in the cerebellum, and pyramidal neurons in the endfolium and Sommer sector of the hippocampus. Muscular paralysis and artificial ventilation minimise late physiological changes such as arterial hypotension and hyperpyrexia, and protect against cerebellar damage, but only slightly against neocortical and hippocampal damage. When arterial hypotension, hypoxia or hypoglycaemia lead to a reduction in the intensity of seizure discharge in paralysed, ventilated rats, there is also a reduction in hippocampal and neocortical damage. Factors intimately related to the intensity and duration of the neuronal discharge are responsible for neocortical and hippocampal lesions.
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PMID:Physiological changes during prolonged seizures and epileptic brain damage. 58 96


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