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

The phenomenon of plasma renin activattion by acid dialysis and preincubation with trypsin was studied in normal human plasma. Activation of plasma renin by exposure to pH 3.3 was shown to require at least one dialysis step and could be inhibited by the presence of Trasylol, indicating the involvement of a protease in acid activation. Amniotic fluid exposed to pH 1.5 to destroy renin and renin substrate was also found to contain an enzyme capable of activating plasma renin. The Michaelis-Menten constant Km and the molecular weight of activated "renin" were found to be similar to those of normal plasma renin. Inactive renins or renin-like enzymes were partially purified from plasma by affinity chromatography on concanavalin A, precipitation with (NH4)2SO4 and isoelectric focusing. Trypsin and acid exposure gave similar results with regard to the activation of this zymogen, suggesting that trypsin and acid dialysis may increase plasma renin activity by the same mechanism.
Hypertension
PMID:Studies on renin activation in normal human plasma. 9 12

Bovine albumin (BA: 2 mg/kg-1, i.v.) produced a fall in systemic arterial blood pressure accompanied by central venous hypertension and bradycardia in pentobarbital-anaesthetized, spontaneously breathing, bovine albumin-sensitized adult domestic fowl. Trasylol (a potent inhibitor of kallikreins) suppressed acute systemic anaphylaxis. Polyphloretin phosphate (an effective antagonist of PGF2alpha) also inhibited the cardiovascular responses to antigen and PGF2alpha. Sodium meclofenamate and phenylbutazone showed varying degree of blockade of cardiovascular responses to exogenously administered chemical mediators (bradykinik, PGF2alpha, SRS-A and to a lesser extent of histamine, 5-HT and acetylcholine) and antigen. Indomethacin (virtually devoid of receptor blocking activities toward exogenously injected chemical mediators) inhibited anaphylaxis. The results of this investigation strongly suggested an important role of vasoactive lipids and polypeptides in avian anaphylaxis.
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PMID:Acute systemic anaphylaxis in adult domestic fowl--possible role of vasoactive lipids and peptides. 31 23

Deoxycorticosterone acetate (DOCA)-salt hypertension was induced in Brown Norway (BN) kininogen-deficient rats (BN-Ka) and normal rats from the same strain (BN-Ki) after nephrectomy. Systolic blood pressure, which was determined by the tail-cuff method, of BN-Ki increased gradually during this treatment. In contrast, the blood pressure of mutant BN-Ka increased rapidly 2 weeks after the onset of the treatment. Urinary excretion of active kallikrein and prokallikrein increased at the same degree in rats of both strains during this treatment. Significant increase in urinary sodium excretion was observed with a tendency to increase in urine volume during the treatment in normal BN-Ki rats, whereas both parameters were essentially not increased in mutant BN-Ka rats, which could not generate urinary kinin. Aprotinin infusion by osmotic minipump to normal BN-Ki rats during the DOCA-salt treatment resulted in significant further increase in the systolic blood pressure.
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PMID:Essential role of kallikrein-kinin system in suppression of blood pressure rise during the developmental stage of hypertension induced by deoxycorticosterone acetate-salt in rats. 128 79

To study the significance of the increased activity of the kallikrein-kinin system described in patients with Bartter's syndrome, we investigated the pressor response to infused angiotensin II in four patients with the syndrome receiving no treatment and during the administration of aprotinin and of indomethacin. Five normal subjects served as controls. Aprotinin is a proteolytic enzyme that inhibits the formation of kinins by inhibiting plasma and glandular kallikrein. Indomethacin, a prostaglandin-synthesis inhibitor, can also inhibit the kallikrein-kinin system and normalizes vascular responsiveness to angiotensin II in Bartter's syndrome. All patients had increased urinary kallikrein and prostaglandin E2 concentrations. Aprotinin significantly decreased the dose of infused angiotensin II required to induce a 20 mm Hg increase in diastolic blood pressure, from 11 +/- 4 ng/kg/min to 7.0 +/- 2.0 ng/kg/min (mean +/- SD; p less than 0.05) in normal subjects and from 135 +/- 57 ng/kg/min to 70 +/- 26 ng/kg/min (p less than 0.05) in the patients with Bartter's syndrome, without significantly changing plasma renin activity, mean control blood pressure, or urinary prostaglandin E2 concentration. Indomethacin normalized the pressor response to angiotensin II in three patients who had been pretreated for 4 days (pressor dose, 10 ng/kg/min) but not in one patient who received a single oral dose of indomethacin 5 hours before the test. Our results suggest that inhibition of the kallikrein-kinin system alone accounts for approximately a 50% decrease in vascular resistance to the pressor effect of angiotensin II in Bartter's syndrome, while additional suppression of prostaglandins entirely normalizes the vascular response to angiotensin II.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension
PMID:Inhibition of the kallikrein-kinin system and vascular reactivity in Bartter's syndrome. 241 84

Aprotinin, the serine protease inhibitor that also inhibits glandular (urinary) kallikrein, or vehicle was infused into the aorta above the renal arteries of anesthetized pigs. Renal hemodynamic and functional parameters were followed over time and during hemorrhagic hypotension. Both renal cortical blood flow and glomerular filtration rate were maintained in vehicle-treated animals at mean arterial pressures as low as 70 mm Hg. As long as renal cortical blood flow and glomerular filtration rate were maintained during the progressive hypotension, urinary excretion rate of kallikrein (as defined by kinin-generating activity) was increased. In contrast, all aprotinin-treated animals had a decreased excretion rate, and the renal cortical blood flow declined with the mean arterial pressure during hemorrhage. The pattern of glomerular filtration rate and plasma renin activity was comparable in both aprotinin-treated and vehicle-treated hemorrhaged animals. Our findings suggest that the endogenous renal kallikrein-kinin system is required for functional renal vasodilatation to maintain renal cortical blood flow during hemorrhage and is therefore directly or indirectly responsible for adjustment of preglomerular resistance.
Hypertension
PMID:Effect of the protease inhibitor aprotinin on renal hemodynamics in the pig. 257 4

1. The effect of aprotinin-induced blockade of the kallikrein-kinin system on haemodynamic and biochemical responses to converting enzyme inhibition by SQ 14 225 was evaluated in 26 patients with essential hypertension. 2. SQ 14 225 lowered blood pressure in high, normal and low renin hypertension. In low and normal renin patients, but not in high renin patients, the acute blood pressure-lowering effect of SQ 14225 could be overcome by aprotinin. Aprotinin infusion produced small vasopressor effects in all groups of patients. 3. Aprotinin lowered the level of circulating active renin but not that of inactive renin. 4. It is concluded that in low and normal, but not in high, renin hypertensive patients activation of the kallikrein-kinin system is responsible for the acute blood pressure reduction observed with converting enzyme inhibitions. 3. Aprotinin lowered the level of circulating active renin but not that of inactive renin. 4. It is concluded that in low and normal, but not in high, renin hypertensive patients activation of the kallikrein-kinin system is responsible for the acute blood pressure reduction observed with converting enzyme inhibition. 5. With long-term converting enzyme inhibition kallikrein-kinin system activation seems to play only a minor role. 6. The kallikrein-kinin system may be involved in the regulation of blood pressure. 7. There is no direct evidence of a participation of kallikrein in the activation of prorenin in vivo.
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PMID:Altered blood pressure and renin responses to converting enzyme inhibition after aprotinin-induced kallikrein-kinin-system blockade. 616 Sep 38

Transient shock in the form of systemic hypotension and portal venous hypertension has accompanied the portal vein infusion of pancreatic mixed cell autografts in human and canine recipients. The use of aprotinin and/or heparin has been suggested as blocking agents for this vascular reaction. The supernatant from the collagenase-digested pancreatic cells contains the pancreatic shock factor (PSF). A total of 45 animals were studied: 15 mongrel dogs, 15 domestic pigs, and 15 Rhesus monkeys. Femoral artery pressure (FAP), portal venous pressure (PoVP), and cardiac output were recorded continuously. Each animal received 0.05 ml/kg of autologous PSF intravascularly. Each animal species was then divided into three study areas containing five animals with Study 1 receiving PSF plus increasing doses of aprotinin (2,500, 5,000 and 10,000 KIU/kg); Study 2, full heparinization and then PSF; and Study 3, full heparinization and then PSF plus aprotinin. The same vascular hemodynamic factors were measured. Aprotinin blocked the entire shock reaction in the pig (FAP and PoVP), only partially blocked the PoVP elevation in the dog, and blocked neither FAP nor PoVP changes in the monkey. Heparinization did not change the shock reaction in any animal species nor did it change the response to aprotinin blockade in any species. A species response variability exists between the dog, pig, and monkey when aprotinin is injected to block PSF obtained from the animal's own pancreas. If the primate and human responses to aprotinin blockade are similar, aprotinin and/or heparin should not prevent the transient shock associated with human pancreatic mixed cell autotransplantation.
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PMID:Hemodynamic measurements after administration of aprotinin and/or heparin during pancreatic cell autotransplantation in the dog, pig, and monkey. 617 85

We studied the effect of aprotinin, a reversible inhibitor of kallikrein and other serine proteases, upon urinary kallikrein and kinin excretion, renal function and hemodynamics, blood pressure, and plasma renin activity (PRA). When aprotinin was administered to anesthetized rats at 10,000 KIU/kg as a bolus, and at 1000 KIU/kg/min infusion for 60 minutes, urinary kininogenase activity and immunoreactive kallikrein, kinins, sodium, potassium, and water excretion, and PRA decreased significantly. Aprotinin also caused a 36% decrease (p less than 0.001) in renal blood flow (RBF), and a 37% decrease (p less than 0.001) in glomerular filtration rate (GFR), although neither blood pressure nor cardiac output changed. The effect of aprotinin on PRA was further studied in conscious rats before and after stimulation of renin release by isoproterenol or furosemide. Aprotinin (5,000 KIU/kg bolus and 1000 KIU/kg/min infusion for 60 minutes) did not alter basal or isoproterenol-stimulated PRA, but it blunted the increase in PRA as stimulated by furosemide. Aprotinin at a higher dose (20,000 KIU/kg bolus and 5000 KIU/kg/min infusion for 60 minutes) significantly lowered blood pressure and increased hematocrit and PRA. These effects may be due to inhibition of serine protease(s) or to other as yet unrecognized properties of this peptide resulting from its highly cationic nature. In conclusion, aprotinin at a low dose decreased kallikrein, kinin, sodium, and water excretion. These decreases may be due to the inhibition of kallikrein and/or other serine proteases or may be secondary to the renal hemodynamic changes.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension
PMID:The effect of aprotinin (a serine protease inhibitor) on renal function and renin release. 619 74

Many properties of urinary kallikrein are well characterized, but the intracellular processing of prokallikrein and release by kidney cells have yet to be clarified. We report here on the synthesis of prokallikrein in Madin-Darby canine kidney (MDCK) cells transfected with rat submaxillary gland kallikrein cDNA and on its activation by MDCK cells and by an enriched liver Golgi membrane preparation. Transfected MDCK cells secreted only prokallikrein at both the apical and basolateral sides in about a 4:1 ratio, but cells transfected with kallikrein cDNA in reverse orientation or untreated cells released only traces of the enzyme. Prokallikrein, in culture medium or in homogenized MDCK cells, was fully activated by trypsin but activated only to 44% by thermolysin. Prokallikrein was synthesized and released into the medium at a high rate: the enzyme secreted by 5 x 10(6) cells in 24 hours cleaved 46 nmol/min D-Val-Leu-Arg-7-amino-4-methylcoumarin and liberated 63 ng/min bradykinin after activation. Immunocytology indicated the association of prokallikrein with the Golgi apparatus in the transfected cells. Antiserum to rat urinary kallikrein detected a single band in a Western blot of conditioned medium and also immunoprecipitated the enzyme. Aprotinin inhibited activated prokallikrein. Although MDCK cells released prokallikrein, their homogenates activated prokallikrein at both pH 5.5 and 7.5. Prokallikrein was also activated by a highly enriched liver Golgi membrane fraction and by an endoplasmic reticulum preparation, but the Golgi preparation was 38-fold more active. The activation was blocked significantly by inhibitors of serine proteases and less by cysteine protease inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1995 Dec
PMID:Expression of rat kallikrein and epithelial polarity in transfected Madin-Darby canine kidney cells. 749 Jan 45

We have examined whether exogenous human tissue kallikrein exerts pharmacological actions via the bradykinin B2 receptor; specifically, whether the protease can bind to, cleave, internalize, and/or activate a fusion protein composed of the rabbit B2 receptor conjugated to the green fluorescent protein (B2R-GFP). The enzyme partially digested the fusion protein at 1 micromol/L, but not 100 nmol/L, and promoted B2R-GFP endocytosis in HEK 293 cells (> or =50 nmol/L). Trypsin and endoproteinase Lys-C, but not plasma kallikrein, also cleaved B2R-GFP. Phospholipase A2 was activated by 50 nmol/L tissue kallikrein in HEK 293 cells expressing B2R-GFP, and this was mediated by the receptor, as shown by the effect of a B2 receptor antagonist and by the lack of response in untransfected cells. However, 500 nmol/L kallikrein elicited a strong receptor-independent activation of phospholipase A2. Tissue kallikrein competed for [3H]bradykinin binding to B2R-GFP only at 1 micromol/L. A simulation involving kallikrein treatment of HEK 293 cells, pretreated or not with human plasma, evidenced the formation of immunoreactive bradykinin. The enzyme (50 nmol/L) contracted the rabbit isolated jugular vein via its endogenous B2 receptors, but the effect was tachyphylactic, and there was no cross-desensitization with bradykinin effects. Aprotinin prevented all pharmacological responses to tissue kallikrein, indicating that the enzyme activity is required for its effect. The local generation of kinins is a plausible mechanism for the pharmacological effects of lower concentrations of tissue kallikrein (50 to 100 nmol/L); higher levels (0.5 to 1 micromol/L) can not only initiate the degradation of rabbit B2 receptors but also exert nonreceptor-mediated effects.
Hypertension 2003 Mar
PMID:Tissue kallikrein actions at the rabbit natural or recombinant kinin B2 receptors. 1283 33


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