Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prostaglandins (PG) A1, B1, E2, F2 alpha and plasma renin activity (PRA) were measured by radioimmunoassay in 8 patients with unilateral artery stenosis, 7 hypertensive patients with unilateral renal atrophy without stenosis ans 20 controls. The measurement of the PG and PRA in the hypertensive group was performed in the infra-renal inferior vena cava and in the two renal veins. PRA and PGA1 were significantly raised in the renovascular hypertensive patients but no significant change was observed in the group with unilateral renal atrophy. On the other hand, the PGE2 and PGF2 alpha were raised in both groups, especially in the renal veins on the stenosed or atrophic side. There was a positive significant correlation between PRA and PGA1 and PGB, but none with PGE2 or PGF2 alpha. This study suggests that the increase in PGA1 and PGE2 represents a secondary hypertensive mechanism which is diuretic and natiuretic. The increase of PGF2 alpha represents a direct mechanism of hypertension. Simultaneous measurement of the vasopressor (PRA and PGF2 alpha) and vasodepressor (PGA and PGE) systems may give a better diagnostic and prognostic approach to renovascular hypertension.
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PMID:[Prostaglandins in renovascular arterial hypertension]. 11 9

1. The renin present in human amniotic fluid was found to have an apparent Mr of 58 000 by gel filtration and is thus bigger than renin in untreated kidney extracts and plasma (Mr approximately 40 000). 2. Treatment with pepsin (40 microgram/ml pH 4.8, 2 h, 22 degrees C) caused a 6-fold increase in activity of this renin species, although Mr was not very different (57 000). 3. Unlike renal renin, renin in human amniotic fluid was not a glycoprotein and behaved similarly on concanavalin A-Sepharose before and after activation by pepsin. 4. Ion-exchange chromatography demonstrated a small change in the ionization properties of human amniotic fluid renin after activation by pepsin. 5. Pepsin-mediated activation resulted in a five-fold increase in V, but only a small decrease in the Km of renin to 39% of normal, so that the increase in activity observed was not due to an increase in the affinity of the enzyme for its substrate. The kinetic data were consistent with the theory of noncompetitive inhibition. 6. The activation of human amniotic fluid renin by pepsin may be caused by a change in the tertiary structure of the molecule subsequent to a proteolytic action that does not remove detectable polypeptide components.
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PMID:Properties of the activation by pepsin of inactive renin in human amniotic fluid. 36 68

We examined the hypothesis that the vascular abnormalities of Bartter's syndrome are due to excess production of prostaglandin. Balance studies and vascular reactivity studies were performed before and after indomethacin (200 mg/day) in a patient with well-documented Bartter's syndrome. During indomethacin, potassium balance became positive, serum potassium rose from 2.1--3 mEq/1 in the absence of potassium supplementation, plasma renin activity decreased from 55--3.2 ng/day and peripheral plasma PGA-like activity fell from 1460 +/- 220 to 456 +/- 71 pg/ml. Before indomethacin, forearm vasoconstrictor responses to brachial arterial infusions of angiotensin II, norepinephrine and to neurogenic reflex stimulation elicited by lower body suction were greatly depressed compared to those of normal subjects. During indomethacin these responses were restored to normal. The dose of intravenous angiotensin II required to increase diastolic blood pressure 20 mm Hg decreased from 160--30 ng/kg/min. These data support the hypothesis that the vascular insensitivity to exogenous angiotensin II, norepinephrine and to neurogenic reflex stimulation observed in this patient with Bartter's syndrome is due to excess prostaglandin. Moreover, stimulation of the renin-angiotensin-aldosterone system in this syndrome appears to be a compensatory adaptation to excess prostaglandin production.
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PMID:Effects of indomethacin on the vascular abnormalities of Bartter's syndrome. 67 46

The role of PGA on the release of renin in the anesthetized dog has been studied. The infusion of prostaglandin for 60 minutes at a dose unable to cause pressor modifications (2 microgram/kg/min) was shown to increase the plasma renin activity (PRA); this effect was inhibited by propranolol and strengthened by aminophylline.
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PMID:Effect of prostaglandin A on renin secretion in the dog. 74 59

In addition to its well known prohypertensive role in various states of experimental and human hypertension, the kidney has also been shown to exert an antihypertensive "endocrine" function. According to this hypothesis, certain forms of experimental and human hypertension might not solely be the result of an excess in the activity of such renal pressor systems as the renin-angiotensin system and the sympathetic nervous system, but might also result from an absolute or relative deficiency of intra-renal vasodilator antihypertensive factors which might allow pressor systems to act unopposed to produce peripheral arteriolar vasoconstriction and sustained hypertension. At least four factors have been characterized in the kidney of various animal species and man which might be responsible for such an antihypertensive function. These are (1) the renomedullary prostaglandins (PGs), (2) the renomedullary antihypertensive neutral lipid, (3) antirenin phospholipid and (4) the renal kinins. This review is restricted to an examination of the possibility that the vasodepressor renomedullary prostaglandins (PGA and/or PGE) may, at least in part, mediate the so-called antihypertensive function of the kidney and participate in the regulation of renal blood flow and natriuresis by physiologic antagonism of various renal vasoconstrictor stimuli such as the renal renin-angiotensin and the sympathetic nervous systems.
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PMID:Renal prostaglandins and the regulation of blood pressure and sodium and water homeostasis. 79 89

The effect of angiotensin II on peripheral levels of immunoreactive prostaglandin A2 (IR-PGA) was determined in 17 normal male volunteers. IR-PGA rose from 338 +/-65 (SE) pg/ml to 635+/-142 in response to pressor infusions of angiotensin II (p less than 0.05 on paired analysis). This increase was not observed when indomethacin, 75 mg p.o., was given to 8 patients two hours prior to a repeat infusion. Five patients of the original group were placed on a low sodium diet (10-20 mEg). The response to angiotensin was now exaggerated (278+/-52 pg/ml to 916+/-284). These five patients were kept on a low sodium intake and given indomethacin 50 mg p.o. g 6 hourly for 4 days. There was no significant rise with angiotensin infusion (106+/-31 pg/ml to 120+/-70). Pressor infusions of angiotensin II raise peripheral levels of IR-PGA, and this response is exaggerated by a low sodium diet and blocked by either acute or chronic indomethacin administration. This data supports the concept that vasodilatory prostaglandins may be released by endogenous angiotensin and thus provide a dynamic antagonism to the renin angiotensin system in man.
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PMID:The effect of angiotensin II and indomethacin on immunoreactive prostaglandin "A" levels in man. 94 20

Prostaglandins PGE-1 or PGA-1 (0.5 to 1 mug per min) were infused into the stenosed renal artery of anesthetized hypertensive dogs. Increased urine volume, sodium and potassium excretion, and p-aminohippurate clearance were found during the prostaglandin infusion period in the infused kidney as compared to the control periods before infusion. Creatinine clearance was increased during infusion of PGE-1. The noninfused, nonischemic kidney showed no effect at the time of infusion with PGE-1 but in the case of PGA-1, the p-aminohippurate and creatinine clearances and urine diuresis were decreased. As a result, the mean aortic blood pressure decreased. Both prostaglandins increased the renal vein renin in the infused kidney. PGA-1 did affect renin release of the noninfused kidney, but PGE-1, which is rapidly inactivated by the lung, did not have this effect. Renin release seems to be influenced by electrolyte diuresis operating through the macula densa mechanism. However, the lowering of blood pressure seen in this study cannot exclude the involvement of the stretch receptors (the juxtaglomerular cells) for renin release. The increased renin release after prostaglandin administration seems to be a protective renal mechanism against the drug-induced hypotension. It seems to be induced by the direct sodium and water diuretic effects of prostaglandins.
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PMID:Direct effect of prostaglandins in renal function and renin release in the presence of renal ischemia in the dog. 111 61

BW-175 is a newly synthesized renin inhibitor which is a nonpeptidic, norleucine analog. Its IC50 values for renin activity in human, squirrel monkey, marmoset, dog, hog, rabbit and rat plasma were 3.3, 6.6, 2.4, 42, 110, 86 and 3500 nM, respectively, and 26 microM for cathepsin D. Pepsin and angiotensin converting enzyme were hardly inhibited at 10(-4) M. BW-175 showed an oral bioavailability of 2.8% at 10 mg/kg and 9.7% at 30 mg/kg in rats. In normotensive, furosemide-treated high-renin marmosets, BW-175 (30 mg/kg p.o.) caused an intensive reduction in plasma renin activity and plasma angiotensin I formation, associated with a reduction in systolic blood pressure of 10-20 mm Hg for 2 hours.
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PMID:A novel nonpeptidic, orally active renin inhibitor. 249 4

Treatment of animal and human plasmas with pepsin yielded large quantities of immunoreactive methionine5-enkephalin (i-met-ENK). The concentrations measured after pepsin treatment were 0.1-0.5 microM, about 1000 times the normal circulating level of i-met-ENK (0.03-0.3 nM). The reaction was shown to be time and pH dependent and to involve the action of pepsin on a protein(s) of about 65,000 mol wt. Pepsin-generated i-met-ENK from rat plasma gave three major peaks during reverse phase HPLC, one of which (approximately 25% of the total) coeluted with methionine5-enkephalin sulfoxide and also completed in a radioreceptor assay for opiate-related substances. In addition, this material produced met-ENK-like effects on vascular permeability in rat skin and inhibited electrically induced contractions of the isolated guinea pig ileum in a naloxone-sensitive manner. The plasma substrate(s) that yielded i-met-ENK was distinguished from adrenal proenkephalins, since partially purified plasma substrate(s) did not liberate i-met-ENK upon digestion with trypsin and carboxypeptidase B. Although it is possible that these peptides differ from met-ENK in amino acid sequence, the results presented here suggest that met-ENK-related substances might be formed physiologically by the action of a pepsin-related processing enzyme(s) on plasma substrate(s). Such a mechanism would be analogous to that used in the renin-angiotensin system.
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PMID:Plasma protein(s) yields met-enkephalin-related peptides in near-micromolar concentrations when treated with pepsin. 309 94

Treatment of mammalian plasmas with pepsin yielded extraordinary quantities of immunoreactive neurotensin (iNT) and methionine5-enkephalin (iENK). The concentrations measured after pepsin-treatment (iNT, 1-5 microM and iENK, 0.1-0.5 microM) were 1-100 thousand times the normal circulating levels of these peptides. The reactions were shown to be time, temperature and pH dependent and to involve the action of pepsin on albumin-like proteins (Mr, ca, 65,000). Pepsin-generated iNT from rat plasma differed from NT since it reacted only with C-terminal directed antisera and eluted earlier than NT during HPLC on mu-Bondapak C-18. Partially purified iNT was active in two bioassays for NT, one which senses changes in vascular permeability to protein after intradermal injection into rats and another which measures release of histamine from isolated rat mast cells. Other biologic activities generated by pepsin-treating plasma included effects on systemic blood pressure in rats and on the contractility of the isolated guinea pig ileum. Some of these, however, were attributable to the formation of angiotensin- and bradykinin-related peptides. Pepsin-generated iENK gave three major peaks during HPLC, one of which (ca, 25%) co-eluted with oxidized ENK and also registered in a radioreceptor assay for opiate-related substances. In addition, this material produced ENK-like effects on the isolated guinea pig ileum and on vascular permeability in rat skin. The precursor-like protein(s) for iENK were distinguished from adrenal proenkephalins since it did not liberate iENK upon digestion with trypsin and carboxypeptidase B. Since pepsin can mimic renin these results suggest the existence of systems in blood (analogous to the renin/angiotensin system) for the generation of biologically active NT- and ENK-related peptides and they also raise the question as to whether other neuropeptides might be found circulating in precursor form(s).
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PMID:Generation of immunoreactive neurotensin(s) and enkephalin(s) by pepsin-treatment of plasma. 310 14


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