Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.15 (renin)
 35,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Present knowledge of the mechanisms regulating release of renin is reviewed with particular emphasis on neural factors. Evidence is given for a direct effect of renal innervation on beta adrenergic receptors in juxtaglomerular cells, and for the involvement of reflex release of renin in conditions such as tilting and acute salt depletion. Participation of neural and nonneural mechanisms of control is also shown to occur in other conditions, such as aortic constriction and hemorrhage. The view is held that neural sympathetic factors might explain some of the renin disturbances found in essential hypertension. First, in patients with high renin hypertension part of the hypertension is renin-dependent, and these pressor levels of renin seem to be neurally induced since they can commonly be suppressed by beta adrenoreceptor blocking agents. Second, the hypothesis is presented that patients with low renin hypertension, at least those who have no volume disturbance, have a blunted sympathetic control of renin release. Therefore a sufficiently precise test of sympathetic activity, and possibly of body fluid volumes, should be associated with renin profiles for a better understanding of the pathophysiology of arterial hypertension and as a better guide to therapeutic management. Indeed, most of the available antihypertensive drugs act on sympathetic activity, body fluid volume or renin, and this multifaceted profile would provide more rational guidelines for treatment.
 ...
PMID:Control of renin release: a review of experimental evidence and clinical implications. 0 64

dl-Propranolol (0.8-1.6 mg/kg - h for 1 h) produced a transient two- to three-fold increase in sodium excretion in nondiuretic rats infused with Pitressin and aldosterone and in water diuretic rats. Sodium excretion increased more in rats depleted of renin by chronic Doca and salt administration than in rats maintained on a low salt diet. An angiotensin inhibitor (1,sarcosine-8,valine angiotensin II) decreased sodium excretion. Therefore the natriuresis was not mediated by antidiuretic hormone, aldosterone, or renin-angiotensin. d-Propranolol did not produce a natriuresis. Prior treatment with phenoxybenzamine did not prevent the natriuretic response but chlorisondamine pretreatment did. The natriuresis is produced by beta blockade and requires post ganglionic nerve function but is independent of alpha receptors. dl-Propranolol decreased heart rate and cardiac output but systemic pressure did not fall and renal blood flow increased. This suggests a dopamine-mediated renal vasodilation and natriuresis. Haloperidol and pimozide, both dopamine blocking agents with minimal beta blocking effects, prevented the natriuretic response. We conclude that propranolol may increase sodium excretion directly by blocking beta receptors in the distal nephron and indirectly by dopamine-mediated renal vasodilation.
 ...
PMID:Propranolol induces acute natriuresis by beta blockade and dopaminergic stimulation. 1 Oct 39

1. The morphology of the juxtaglomerular apparatus, plasma renin activity, plasma renin substrate and renal renin have been studied in rats after maximal stimulation by bilateral adrenalectomy and salt depletion, and also after blocking this stimulation by deoxycorticosterone and salt load. 2. After stimulation the juxtaglomerular apparatus showed a well-developed granular endoplasmic reticulum and a low secretory granule content. Plasma renin activity was markedly elevated and plasma renin substrate was low. After blockade numerous specific granules with crystalline structures were seen and the granular endoplasmic reticulum was less developed. Plasma renin activity was now low and plasma renin substrate elevated. 3. After prior acidification of the kidney extract a significant increase of renal renin was observed in both conditions but was greater in the second group at the time when large numbers of young granules containing crystalline material were seen. 4. Kidney slices from the adrenalectomized salt-depleted rats released more renin than control slices. Vincristine did not affect this release, but inhibited release from slices stimulated by isoprenaline.
 ...
PMID:Control of renin secretion in vivo and in vitro in rats: arguments in favour of a precursor form of renin and of a role of a microtubular system. 1 63

Saralasin, an angiotensin II inhibitor was infused in 10 hypertensive patients. A blood pressure reduction was achieved after stimulation of the renin-angiotensin-system by salt depletion. Heart rate and cardiac output failed to compensate for reduction of blood pressure. Thus circulatory reflex-mechanisms are inhibited by saralasin. A direct influence on baroreceptor mechanism and/or catecholamines is probable. Failure of the hypotensive effect of saralasin in salt-depleted patients after administration of beta-blockers supports this hypothesis.
 ...
PMID:[Hemodynamic changes after angiotensin II blockade by saralasin (author's transl)]. 1 45

The changes in plasma renin activity (PRA) during short-term salt depletion (and peroral furosemide on the first day) and after bolus injection of propranolol were compared to the change during long-term treatment with diuretic and with propranolol in 19 patients with benign primary hypertension. A highly significant correlation was found between PRA on short-term and long-term salt depletion (r=0.02). A highly significant correlation was likewise found between initial PRA and decrement of PRA after bolus injection of or long-term treatment with propranolol. Only a weak inverse correlation was found between PRA reached during short-term salt depletion or long-term diuretic treatment and the fall in diastolic BP during long-term treatment (r=0.60). No significant correlation was found between decrease in PRA on propranolol (bolus/long-term) and diastolic BP reduction. It is concluded that the short-term PRA response to salt depletion and propranolol in the individual patient gives a good prediction of the PRA level on long-term diuretic or propranolol treatment, but is of no value in predicting the BP reduction during treatment.
 ...
PMID:Acute and long-term salt depletion and beta-blockade: plasma renin activity response and its relation to blood pressure reduction in long-term treatment. 2 64

We found an acid extract of normal dog kidneys to contain two distinct molecular weight forms of renin-like activity. Gel filtration chromatography showed peaks of activity as estimated molecular weights of 65,000 and 41,000. The high molecular weight fraction (HMW) comprised only 1% of the total activity of the extract. Both HMW and low molecular weight (LMW) fractions were inhibited by anti-human renin antibody and had similar broad pH-dependent activity optima between pH 6.0 and 7.5 in homologous substrate. The Michaelis constant (Km) of HMW was 3.6 times the Km of LMW. Both renins bound reversibly to concanavalin A-Sepharose with comparable affinities. HMW and LMW eluted from DEAE-Sephadex at similar salt concentrations without conversion of HMW to LMW. Transient acidification effected partial conversion of HMW to LMW without changing the total activity. Preincubation of HMW with trypsin increased the activity 40% and effected complete conversion of HMW to LMW. The apparent molecular weight difference between HMW and LMW is probably due to a covalently bound fragment(s) and not to a noncovalently bound moiety such as has been described in the rabbit and the hog. Both HMW and LMW are glycoproteins whose terminal sugar constituents possibly are similar. HMW dog renin is a new molecular form of renin that is convertible to a more active lower molecular weight renin with tryptic proteolysis.
 ...
PMID:Chemical characteristics of a high molecular weight renin from the renal cortex of the dog. 3 May 45

A study was made of the blood plasma renin activity in 63 patients suffering from thyrotoxicosis before the treatment and in 42 healthy individuals. In comparison with the healthy, renin activity was increased in patients with thyrotoxicosis and displayed a positive correlation with the severity of the disease the level of protein-bound iodine, tachycardia and the degree of loss of weight. Stimulation of the renin-angiotensin system by the salt-free diet, hydrochlorthiazide and by placing the body into orthostatic position caused a relatively weaker increase in the renin activity in comparison with such in healthy individuals. Following successful treatment and the occurrence of an euthyroidal state renin activity proved to fall to the normal level. An increased renin activity was combined with increased urinary aldosterone excretion with a normal serum electrolyte level. Such combination pointed to the secondary character of aldosteronism. Block of the alpha- and beta-adrenergic receptors led to reduction in the level of renin activity. Despite the frequent affection of hepatic function there was revealed no correlation between the increase in the renin activity and the pathological results of hepatic tests. Plasma renin activity was reduced in 8 patients with myxedema. It is supposed that the principal factors causing activation of the renin-angiotensin system in thyrotoxicosis were the loss of water and electrolytes by the organism and the appearance of oversensitivity to adrenergic receptors.
 ...
PMID:[State of the renin-angiotensin system in thyrotoxicosis]. 4 92

The effect of infusion of the angiotensin II antagonist P113 on blood-pressure (B.P.) has been studied in 10 patients with various forms of hypertension under four different conditions: before and after salt depletion and with or without propranolol treatment. The fall in B.P. after P113 infusion significantly correlated with log P.R.A. (plasma-renin activity), irrespective of diagnosis or treatment. P113 infusion caused a consistent fall in B.P. only after sodium depletion. The changes in B.P. after P113 infusion and those induced by propranolol correlated only during sodium depletion, when P.R.A. values rose. It is concluded that sodium depletion induced "renin dependency" of B.P. in all patients. The decrease in B.P. renin dependency after propranolol therapy suggests that suppression of P.R.A. is one of the antihypertensive mechanisms underlying the action of this drug.
 ...
PMID:Renin dependency of blood-pressure. Analysis by angiotensin II antagonist P113 in hypertensive patients treated with salt depletion and propranolol. 5 53

Four patients with idiopathic orthostatic hypotension (I.O.H.) and one with postural hypotension and diabetes were studied. Plasma-renin activity (P.R.A.) was low and did not rise appropriately with salt restriction and diuretic stimulation. Aldosterone levels were normal and rose with diuretic therapy. Plasma-volume, plasma dopamine beta-hydroxylase, urinary catecholamines, metanephrines, and vanillyl mandelic acid (V.M.A) were normal. Treatment with indomethacin (75-150 mg/day) raised the upright blood-pressure (B.P.) by an average of 20-30 mm Hg diastolic and allowed the four patients with I.O.H. to walk about without orthostatic symptoms but it had no effect in the fifth patient. When indomethacin was discontinued in one patient who had been taking it for 9 months with symptomatic relief, the B.P. fell to pretreatment levels within 48 h. When indomethacin was reinstituted the B.P. rose again. Indomethacin was more effective in these patients than either propranolol or fludrocortisone. There may be an absolute or relative excess of certain vasodepressor prostaglandins in the peripheral vessels which results in pooling of blood and orthostatic hypotension. If this is the case indomethacin might improve the orthostatic symptoms of I.O.H. by its inhibitory effect on prostaglandin synthesis, but its mechanism of action remains to be determined.
 ...
PMID:Treatment of idiopathic orthostatic hypotension (Shy-Drager syndrome) with indomethacin. 7 34

Normal human plasma contains not only active renin but also an inactive form of renin which, after exposure to low pH, can generate angiotensin I from renin substrate. When healthy volunteers were given first a diet containing 400 mmol sodium and then a diet containing 10 mmol sodium for 4 days the changes in salt intake stimulated large changes in active plasma-renin and smaller changes in inactive renin. Inactive renin comprises a larger fraction of total renin in plasma of salt-loaded healthy subjects than salt depleted subjects. When plasma of healthy men on a high-salt diet was applied to a column of 'Sephadex G-100', renin eluted in two peaks, corresponding to big renin (60 000 daltons) and normal renin of lower molecular weight (40 000 daltons). Active and inactive forms of renin were present in both peaks. Plasma from salt depleted healthy subjects showed a large single peak of renin activity with a maximum at 40 000 daltons. These studies demonstrate that both big and small renin can exist as inactive or active enzyme. Big renin, previously found in certain diseases and in pregnancy, is also present in normal human plasma. These observations suggest a possible physiological role for big renin.
 ...
PMID:Big renin in plasma of healthy subjects on high sodium intake. 7 48


1 2 3 4 5 6 7 8 9 10 Next >>