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

The purpose of this study was to determine whether adenosine can attenuate the renin release response to a reduction in renal perfusion pressure. To this end, the secretion rate of renin was measured in six beta-blocked dogs at ambient arterial blood pressure and after a reduction of renal perfusion pressure to 80 mm Hg. These measurements were made during a control period, an intrarenal infusion of adenosine at 10 and 30 micrograms/min, and a recovery period. During the control and recovery periods renal artery hypotension significantly increased the secretion rate of renin. However, during the intrarenal infusions of adenosine, renin secretion rate did not increase significantly. Analysis of variance indicated that both doses of adenosine reduced the renin response to renal artery hypotension. In another six dogs with a single nonfiltering kidney, we again measured renin secretion during a control period, the intrarenal infusion of adenosine at 10 and 30 micrograms/min, and a recovery period; however, in this study PGI2 was used to stimulate renin release. Adenosine also significantly attenuated the renin release response to PGI2. We conclude that adenosine can inhibit the renin release response to both renal artery hypotension and PGI2 and that this effect is most likely mediated by a direct action of adenosine on juxtaglomerular cells. Also, since PGI2 may be a mediator of the renin response to renal artery hypotension, the data are consistent with the hypothesis that adenosine inhibits the renin response to renal artery hypotension by attenuating the response of juxtaglomerular cells to PGI2.
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PMID:Adenosine inhibits renin release induced by suprarenal-aortic constriction and prostacyclin. 257 Mar 63

We hypothesize that the hemodynamic effects of xanthine derivatives depend on their ability to antagonize the vasodilating effects of endogenous adenosine. In a randomized, double-blind, and placebo-controlled study of 10 normotensive volunteers caffeine, a xanthine with in vitro adenosine antagonistic properties, increased mean arterial pressure by 5.6 +/- 0.9 mm Hg and lowered heart rate by 5.3 +/- 1.1 beats/min. After administration of enprofylline, a xanthine without adenosine antagonism, forearm vascular resistance decreased by 5.6 +/- 3.4 IU, heart rate increased by 10.6 +/- 2.6 beats/min, and plasma adrenaline, plasma noradrenaline, and renin activity increased by 178 +/- 86%, 14 +/- 8%, and 36 +/- 13%, respectively. Adenosine infusion alone induced a dose-related increase in pulse pressure and heart rate, and it increased plasma adrenaline and noradrenaline by 186 +/- 77% and 132 +/- 55%, respectively. This response to adenosine was reduced by pretreatment with caffeine but not enprofyline. Thus opposite circulatory responses to caffeine and enprofylline occurred, with signs of vasoconstriction and vasodilation, respectively. In addition, caffeine, but not enprofylline, reduced the cardiovascular response to exogenous adenosine.
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PMID:Cardiovascular effects of two xanthines and the relation to adenosine antagonism. 265 34

Adenosine is a potent inhibitor of renin release. It has therefore been suggested that endogenous adenosine may play a role in the regulation of renin release. Sodium-chloride transport at the level of the macula densa has been proposed as the primary source of endogenous adenosine. Evidence to support a modulatory role of adenosine on renin release in vivo is, however, limited. We therefore wanted to determine if: 1) adenosine modulates furosemide-induced renin release and 2) sodium-chloride reabsorption at the macula densa is essential for adenosine actions. To test these hypotheses, three groups of rats were pretreated either with saline or the adenosine receptor antagonists caffeine or 1,3-dipropyl-8-(p-sulfophenyl)xanthine (both at a dose of 30 mg/kg followed by 450 micrograms/kg/min). Rats then received furosemide (50 mg/kg i.v.). In the vehicle group, furosemide increased urinary volume, sodium and potassium excretion and increased plasma renin activity from 6 +/- 1 to 45 +/- 11 ngAl/ml/hr. Caffeine and 1,3-dipropyl-8-(p-sulfophenyl)xanthine potentiated the increase in plasma renin activity produced by furosemide (to 120 +/- 15 and 147 +/- 21 ng Al/ml/hr, respectively), whereas having no significant effects on urinary volume, sodium excretion or blood pressure. These results suggest that furosemide-induced renin release in vivo is restrained by endogenous adenosine. In as much as furosemide blocks sodium-chloride transport in the thick ascending limb of Henle's loop and the macula densa cells, it appears that under the conditions of this study sodium transport across these segments is not essential to initiate adenosine-mediated mechanisms.
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PMID:Caffeine potentiates the renin response to furosemide in rats. Evidence for a regulatory role of endogenous adenosine. 267 16

Intrarenal adenosine could be a physiological regulator of glomerular filtration rate and renal blood flow, acting on the renal arteriolar tone. Recent experimental evidence strongly suggests an important role for intrarenal adenosine in the hemodynamic renal changes observed in ischemic acute renal failure (ARF), as well as in various other experimental models of ARF. Adenosine also appears to play a key role in the hypoxemia-induced renal insufficiency in newborn animals. The deleterious functional changes induced by hypoxemia can be prevented by low-dose theophylline, a xanthine with strong adenosine antagonistic properties. The overall experimental data suggest that adenosine vasodilates the efferent glomerular arteriole and vasoconstricts the afferent arteriole when the renin-angiotensin system is stimulated.
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PMID:Adenosine in the immature kidney. 269 97

Adenosine is known to be a potent inhibitor of renin release from the kidneys. The aim of this study was to investigate the transmembrane signalling avenue that the second messenger of adenosine causes inhibition of renal renin release. Using short term cultures of juxtaglomerular cells isolated from rat kidneys, we found that adenosine inhibited spontaneous renin release from these cells up to 40% of control, in a dose dependent fashion between 10(-10) M to 10(-6) M. Half maximal inhibition was observed at 2 X 10(-8) M adenosine. The inhibitory effect of adenosine on renin release could be mimicked by the A1-receptor agonist N6-cyclohexyladenosine (CHA) and could be attenuated by the A-receptor antagonist theophylline (5 X 10(-5) M). The A2-receptor agonist 5'-N-ethylcarboxamideadenosine (NECA) had no inhibitory effect on renin release. These findings indicate that the inhibitory effect of adenosine is mediated by A1-receptors on juxtaglomerular cells. Adenosine had no effect on either transmembrane calcium influx or the cytosolic free calcium concentration in the isolated juxtaglomerular cells. Adenosine also did not alter the cellular level of cyclic AMP in the concentration range employed. However, adenosine led to a dose dependent increase of the cellular level of cyclic GMP. Half maximal increase of cGMP was observed at 10(-8) M adenosine. The effect of adenosine on cyclic GMP could be mimicked by the A1-receptor agonist CHA and could be attenuated by the A-receptor antagonist, theophylline.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of cGMP as second messenger of adenosine in the inhibition of renin release. 283 80

Studies were performed in normal dogs (n = 6) and dogs with nonfiltering kidneys (n = 8) to determine the effects of synthetic atrial natriuretic peptide (ANP) on renin secretion and renal hemodynamics in the presence and absence of a functional macula densa. In normal dogs, intrarenal infusion of ANP (0.3 microgram X kg-1 X min-1) resulted in a decrease in renin secretion from 325.5 +/- 87.4 to 52.4 +/- 29.4 ng/ml, despite a sustained decrease in arterial pressure. In contrast, in the nonfiltering kidney without a functional macula densa, ANP infusion did not inhibit renin secretion in this nonfiltering model. Adenosine, however, known to directly inhibit renin secretion, did decrease renin secretion in this nonfiltering model. The present studies document that, in the nonfiltering kidney, ANP has no inhibitory effect on renin secretion.
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PMID:Effects of atrial natriuretic peptide on renin secretion in nonfiltering kidney. 293 30

Adenosine has been postulated to link control of glomerular filtration rate (GFR) and renal blood flow (RBF) with changes in renal metabolism. In the present study, we examined the role of adenosine in renal autoregulation by comparing the responses of normal anesthetized dogs to step decreases in renal artery pressure (RAP) to the response obtained after receptor blockade of adenosine with aminophylline or by flooding the kidney with exogenous adenosine. In six dogs at normal RAP, intrarenal infusion of aminophylline (10 mumol/min) did not alter renal hemodynamics. GFR and RBF were well autoregulated (greater than 90% of control) at RAP values equal to or greater than 85 mmHg before and after aminophylline. At RAP equal to 75 mmHg, GFR and RBF decreased by 27 +/- 10 and 20 +/- 8%, respectively, before aminophylline and by 25 +/- 7 and 13 +/- 6% after aminophylline. In a different group of six dogs, intrarenal infusion of adenosine (6 mumol/min) significantly increased RBF (32 +/- 9%) and decreased GFR (38 +/- 10%) at normal RAP. However, GFR and RBF were both well autoregulated (greater than 90% of control) at RAP values equal to or greater than 85 mmHg before and after adenosine. At RAP equal to 75 mmHg, GFR and RBF decreased by 10 +/- 5 and 7 +/- 3%, respectively, before adenosine and by 12 +/- 6 and 17 +/- 5% after adenosine. Neither aminophylline nor adenosine attenuated the elevations in plasma renin activity associated with reductions in RAP. These data fail to provide evidence that adenosine is an important factor in autoregulation of GFR and RBF during acute reductions in RAP within the autoregulatory range.
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PMID:Maintenance of renal autoregulation during infusion of aminophylline or adenosine. 298 69

Adenosine analogs selective for the A1 subclass of adenosine receptors, such as N6-cyclohexyladenosine (CHA), inhibit renin secretion in in vitro preparations. Ca chelation blocks the inhibitory effect, consistent with mediation by increased intracellular free Ca2+, and it has been suggested that intracellular Ca2+ could increase as a result of receptor-induced inhibition of adenylate cyclase followed by decreased Ca efflux from the renin-secreting cells. Pertussis toxin blocks receptor-induced inhibition of adenylate cyclase in many cells, and in others, it blocks receptor-induced phosphotidylinositol response. In the present studies, pertussis toxin treatment stimulated the basal renin secretory rate of rat renal cortical slices and blocked the inhibitory effect of CHA but not the inhibitory effect of K-depolarization. These data support the hypothesis that a pertussis toxin substrate, such as Ni, is involved in CHA-, but not in K-depolarization, -induced inhibition of renin secretion.
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PMID:Pertussis toxin reverses adenosine receptor-mediated inhibition of renin secretion in rat renal cortical slices. 302 86

The purpose of these studies was to assess the direct effect of adenosine on the renin release response to beta-adrenoceptor activation in vivo in the canine kidney. In an initial study, innervated, intrarenal beta-adrenoceptors were activated selectively via renal nerve stimulation in kidneys in which the alpha-adrenoceptor response to renal nerve stimulation had been blocked with phentolamine. Adenosine, infused directly into the renal artery (10 and 30 micrograms/min), significantly blunted the renin release response to renal nerve stimulation. However, adenosine also caused significant reductions in base-line glomerular filtration rate, sodium excretion rate, and filtration fraction. To eliminate these confounding effects of adenosine on renal function and to prevent changes in norepinephrine release due to prejunctional inhibition by adenosine, we also studied the effect of intrarenal infusions of adenosine on norepinephrine-induced renin release in the nonfiltering, alpha-adrenoceptor-blocked, canine kidney. In this model of beta-adrenoceptor activation, adenosine abolished the renin release response to intrarenal infusions of norepinephrine. In a final series of experiments, the effect of adenosine on the renin response to dibutyryl-adenosine 3',5'-cyclic monophosphate (cAMP) was examined in the nonfiltering, beta-adrenoceptor-blocked, canine kidney. In this model of cAMP-induced renin release, adenosine was ineffective in attenuating the renin release response. These data demonstrate that in vivo adenosine directly inhibits beta-adrenoceptor-mediated renin release by a mechanism that does not involve a reduction in the ability of cAMP to activate intracellular mechanisms leading to renin release.
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PMID:Adenosine inhibits beta-adrenoceptor but not DBcAMP-induced renin release. 302 56

Adenosine, a direct degradative product of 5'AMP, could be a physiological regulator of glomerular filtration rate and renal blood flow, acting on the renal arteriolar tone and the tubuloglomerular feedback mechanism. Recent experimental evidence strongly suggests an important role for intrarenal adenosine in the hemodynamic renal changes observed in postocclusive acute renal failure, in hypoxemia-induced renal insufficiency, as well as in various experimental models of acute renal failure. In these conditions, adenosine appears to induce predominant postglomerular vasodilatation, as well as preglomerular vasoconstriction when the renin-angiotensin system is activated. Theophylline, a xanthine with strong adenosine antagonistic properties, prevents the hypoxemia-induced renal changes, while enprofylline, a xanthine devoid of such properties, does not prevent these changes. Available data favor the hypothesis that intrarenal adenosine is involved in the pathophysiology of the renal changes observed in the early phase of vasomotor nephropathy.
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PMID:Functional renal insufficiency: role of adenosine. 304 70


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