Inhibition of angiotensin-converting enzyme with quinapril (CI-906): investigation of antihypertensive mechanisms in spontaneously hypertensive rats

Treatment for 8 days with a new nonsulfhydryl angiotensin-converting enzyme inhibitor, quinapril (CI-906), produced a marked and progressive reduction in the blood pressure of spontaneously hypertensive rats. Quinapril was given p.o. in a dose of 20 or 40 mg/kg once daily. Both doses increased plasma renin activity and decreased the urinary excretion of aldosterone. These results, together with a marked decrease in serum angiotensin-converting enzyme activity, indicate that the drug produced a considerable fall in circulating angiotensin II. The urinary excretion of vasopressin was not altered by the smaller dose of quinapril but was reduced by the larger dose, which increased water intake and urine excretion. Quinapril did not affect plasma kininogen or the urinary excretion of kallikrein. The urinary excretion of neither the prostacyclin metabolite 6-keto-prostaglandin F1 alpha nor the thromboxane metabolite thromboxane B2 were altered by the drug. However, quinapril did produce a temporary decrease in the excretion of prostaglandin E2, the effect passing off with the continuation of the treatment. These data indicate that vasodilatory prostanoids do not contribute to the blood pressure lowering effect of quinapril in spontaneously hypertensive rats. The inhibition of the renin-angiotensin system is probably the principal mechanism of the drug's antihypertensive action, but these results do not rule out the possibility that an increase in vasodilatory kinins may also be involved.     

Evidence for renal kinins as mediators of amino acid-induced hyperperfusion and hyperfiltration in the rat.

This study examined the role of tissue kallikrein and kinins in renal vasodilation produced by infusion of amino acids (AA). In rats fed a 9% protein diet for 2 wk, intravenous infusion of a 10% AA solution over 60-90 min reduced total renal vascular resistance and increased glomerular filtration rate (GFR) by 25-40% and renal plasma flow (RPF) by 23-30% from baseline. This was associated with a two- to threefold increase in urinary kinin excretion rate. Acute treatment of rats with aprotinin, a kallikrein inhibitor, resulted in deposition of immunoreactive aprotinin in kallikrein-containing connecting tubule cells and inhibited renal kallikrein activity by 90%. A protinin pretreatment abolished the rise in urinary kinins and prevented significant increases in GFR and RPF in response to AA. In a second group of rats pretreated with a B2 kinin receptor antagonist, [DArg Hyp3, Thi5,8 D Phe7]bradykinin, AA infusion raised urinary kinins identically as in untreated controls, but GFR and RPF responses were absent. Aprotinin or the kinin antagonist produced no consistent change in renal function in rats that were not infused with AA.AA-induced increases in kinins were not associated with an increase in renal kallikrein activity. Notably, tissue active kallikrein level fell 50% in AA-infused rats. These studies provide evidence that kinins generated in the kidney participate in mediating renal vasodilation during acute infusion of AA.     

The Kallikrein-Kinin System in Bartter''s Syndrome and Its Response to Prostaglandin Synthetase Inhibition

The kallikrein-kinin system was characterized in seven patients with Bartter's syndrome on constant metabolic regimens before, during, and after treatment with prostaglandin synthetase inhibitors. Patients with Bartter's syndrome had high values for plasma bradykinin, plasma renin activity (PRA), urinary kallikrein, urinary immunoreactive prostaglandin E excretion, and urinary aldosterone; urinary kinins were subnormal and plasma prekallikrein was normal. Treatment with indomethacin or ibuprofen which decreased urinary immunoreactive prostaglandin E excretion by 67%, decreased mean PRA (patients recumbent) from 17.3+/-5.3 (S.E.M.) ng/ml per h to 3.3+/-1.1 ng/ml per h, mean plasma bradykinin (patients recumbent) from 15.4+/-4.4 ng/ml to 3.9+/-0.9 ng/ml, mean urinary kallikrein excretion from 24.8+/-3.2 tosyl-arginine-methyl ester units (TU)/day to 12.4+/-2.0 TU/day, but increased mean urinary kinin excretion from 3.8+/-1.3 mug/day to 8.5+/-2.5 mug/day. Plasma prekallikrein remained unchanged at 1.4 TU/ml. Thus, with prostaglandin synthetase inhibition, values for urinary kallikrein and kinin and plasma bradykinin returned to normal pari passu with changes in PRA, in aldosterone, and in prostaglandin E. The results suggest that, in Bartter's syndrome, prostaglandins mediate the low urinary kinins and the high plasma bradykinin, and that urinary kallikrein, which is aldosterone dependent, does not control kinin excretion. The high plasma bradykinin may be a cause of the pressor hyporesponsiveness to angiotensin II which characterizes the syndrome.     

Inhibition of prostaglandin synthesis by indomethacin interacts with the antihypertensive effect of atenolol

The interaction of inhibition of prostaglandin (PG) synthesis by indomethacin (75 mg/day) with the antihypertensive effect of atenolol (50 mg b.i.d.) was studied in 11 untreated otherwise healthy men 35 to 45 years old with essential hypertension. Atenolol for 3 weeks decreased supine blood pressure (BP) from 157/109 mm Hg during placebo to 148/97 mm Hg. Indomethacin alone for 1 week slightly increased BP and antagonized the antihypertensive action of atenolol. Atenolol reduced plasma renin activity (PRA) to 40% but did not modify either the urinary excretion of vasodilatory PGs (PGE2 and prostacyclin measured as 6-keto-PGF1 alpha) or plasma kininogen and urine kallikrein. Indomethacin suppressed PRA to 27% and PG excretion to approximately 70% but did not markedly change plasma kininogen and urine kallikrein excretion. The decreased excretion of 6-keto-PGF1 alpha, the metabolite of the main vasodilatory prostanoid prostacyclin, correlated with the increased BP measured in standing subjects. The effects of indomethacin were practically the same when given with atenolol as when given alone. We conclude that the slight increase in BP by indomethacin in essential hypertension is associated with the reduced production of vasodilatory PGs but not with alterations in activities of the renin-angiotensin or kallikrein-kinin systems.     

Inhibition of thromboxane synthetase potentiates the antihypertensive action of an angiotensin-converting enzyme inhibitor by a prostaglandin-dependent but kinin-independent mechanism

Mean arterial pressure (BP) was measured in conscious, spontaneously hypertensive rats (SHR). Oral administration of the angiotensin I-converting enzyme inhibitor (ACEI) CGS 16617 significantly lowered BP. In contrast, the thromboxane synthetase inhibitor (TxSI) CGS 12970 lacked an antihypertensive action in SHR. When administered concurrently, the TxSI significantly potentiated the antihypertensive actions of the ACEI. Inhibition of thromboxane synthetase did not potentiate the antihypertensive actions of metoprolol or verapamil, indicating that a specific interaction exists between a TxSI and an ACEI. The antihypertensive actions of CGS 16617 also were potentiated by the cyclooxygenase inhibitor indomethacin, a result suggesting that CGS 12970 may enhance the action of CGS 16617 by inhibiting the action of vasoconstrictor prostaglandins produced after administration of an ACEI. The potentiation of the antihypertensive actions of CGS 16617 by CGS 12970 remained unaffected by either the kallikrein inhibitor aprotinin or a bradykinin receptor antagonist. Thus, although the interaction between an ACEI and a TxSI is a prostaglandin-dependent mechanism, it is not mediated by endogenous kinins. Inhibition of thromboxane synthetase significantly stimulated renin release and significantly attenuated the pressor response to exogenously administered angiotensin II. An increase in the dependency of BP upon the renin-angiotensin system and attenuation of the vascular actions of angiotensin II may serve to explain the potentiation of the antihypertensive action of ACEI after inhibition of thromboxane synthetase. The interaction between ACEI and TxSI was not restricted to SHR, because a TxSI potentiated the actions of an ACEI in both normotensive and deoxycorticosterone acetate/Na hypertensive rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of cicletanine on vasoactive systems in conscious sinoaortic-denervated dogs

The present study investigates the antihypertensive action of cicletanine, a new antihypertensive compound with diuretic properties (or placebo), on vasopressor (catecholamines, renin-aldosterone) as well as vasodepressor (prostaglandins, kallikrein-kinin) systems in conscious chronic sinoaortic denervated (SAD) dogs. Cicletanine (10 mg/kg twice a day, per os, for one month) lowered blood pressure and heart rate. The antihypertensive action does not involve an effect on sympathetic tone (since plasma catecholamine levels were unmodified) or on plasma aldosterone levels. By contrast, urinary 6 keto PGF1 or PGE2 levels and kallikrein activity were enhanced. This result indicates that the antihypertensive effect of cicletanine is associated with a stimulation of potential vasodepressor systems (such as prostaglandins or kinins).     

The use of the kallikrein-kininogen system indices in the prognosis of the development of hemorrhagic erysipelas]

A number of the kallikrein-kinin system parameters (kallikrein, prekallikrein, total arginine esterase activity, alpha 1 protease inhibitor, and alpha 2 macroglobulin) were measured in 59 patients with erythematous erysipelas and in 51 ones with hemorrhagic erysipelas over the course of the disease. Marked activation of the blood kallikrein-kinin system was seen in all the patients during the initial period of the disease, manifesting by elevated levels of kallikrein, total arginine esterase activity, alpha 1 protease inhibitor, alpha 2 macroglobulin, and a lowered prekallikrein concentration. In erythematous erysipelas the peak of activation was recorded in the first days of the disease, whereas in hemorrhagic condition it was observed during the second week of erysipelatous inflammation. Different patterns of changes in the kallikrein-kinin system over the course of the disease permit using one of its parameters, kallikrein activity, for the prediction of the development of local hemorrhagic syndrome in erysipelas patients already during the earliest (prehemorrhagic) stage of the condition.     

Effect of potassium supplementation on blood pressure and vasodilator mechanisms in spontaneously hypertensive rats

1. Supplementation with 1% (w/v) KCl solution significantly attenuated the blood pressure rise with age normally observed in spontaneously hypertensive rats, resulting in a difference in blood pressure of 18 mmHg after 5 weeks. 2. Urinary 6-keto-prostaglandin F1 alpha (the stable hydrolysis product of prostacyclin) and kallikrein excretion were significantly elevated in rats receiving potassium. 3. No difference was observed in sodium excretion during the initial days of potassium supplementation; however, the potassium-supplemented animals excreted relatively more sodium over the 5 week period. 4. Plasma renin activity was significantly reduced in those animals receiving potassium after 5 weeks. 5. It is proposed that a combination of increased systemic and/or renal prostacyclin and kallikrein synthesis may, in combination with reduced renin activity, contribute to the attenuation of blood pressure in potassium-supplemented spontaneously hypertensive rats.     

Urinary kallikrein and systemic prostacyclin synthesis during sodium chloride infusion in normal man

An intravenous infusion of 3 litres of sodium chloride solution (saline: 150 mmol/l) was given over 1 h to normal subjects. During and immediately after the infusion, renal plasma flow increased in the majority of subjects, but the rise was not statistically significant. Significant increases in urine flow, sodium excretion, urinary kallikrein excretion and urinary excretion of dinor-6-keto prostaglandin (PG) F1 alpha, a measure of systemic PGI2 synthesis, were noted. Plasma renin activity and plasma protein concentration were significantly lowered by the infusion. At 2 h after the end of the infusion, although urine flow fell significantly, sodium excretion had not decreased. The reduction in plasma renin activity and plasma proteins persisted, and excretion of kallikrein and the PGI2 metabolite returned to control values. Overall, urinary kallikrein excretion correlated significantly with urine flow and with sodium excretion. Peak kallikrein excretion occurred in the second 30 min of the infusion, and preceded maximal urine flow and sodium excretion. The results suggest that increased systemic synthesis of PGI2 occurs in response to an acute infusion of sodium chloride, and may be an adaptive response of the vasculature to volume expansion. They support a role for the renal kallikrein-kinin system in the early diuretic and natriuretic response to saline infusion; the reduction in plasma renin activity and plasma protein concentration may be involved in both the early response and the persistent natriuresis 2 h after the infusion.     

Studies on the renin-angiotensin system in a kininogen-deficient individual

The physiological responses of the renin-angiotensin system were studied in an individual with kininogen deficiency (patient 1) with absent plasma bradykinin and markedly impaired pre-kallikrein conversion into kallikrein. After sodium depletion, patient 1 had a low plasma renin activity (1.4 pmol of ANG I h-1 ml-1) and a low angiotensin II concentration (36 pg/ml) compared with values in 11 normal individuals (4.0 +/- 0.94 pmol of ANG I h-1 ml-1) and 63 +/- 6 pg/ml respectively). Unlike normal individuals, in the kininogen-deficient subject there was no significant fall of renin activity or angiotensin II after dietary sodium repletion. Intravenous sodium repletion also failed to further decrease plasma renin activity or angiotensin II. The usual two- to three-fold rise in plasma renin activity and angiotensin II observed in normal subjects on assumption of the upright posture after ingestion of 200 mg of sodium/day failed to occur in the kininogen-deficient individual. These data in vivo are in agreement with observations in vitro that once plasma kallikrein forms it may be important in converting prorenin into renin. In the absence of kininogen, activation of prekallikrein to kallikrein is grossly defective, which may in part account for the diminished response of the renin-angiotensin system to changes in sodium balance and posture.     

Gas exchange, microcirculation and blood kinins in patients with chronic nonspecific lung diseases

The state of gas exchange, microcirculation (MC) and blood kinin was examined in 212 patients with chronic non-specific pulmonary diseases (197 with respiratory insufficiency, 15 without it). Noticeable activation of blood kinins with a rise of kallikrein, a decrease in alpha 2-macroglobulin and kinase activity were revealed in patients with respiratory insufficiency (RI), degree I and II, expressed in MC disorder with perivascular and intravascular changes. Kininogesis suppression with a decrease in all indices was noted in patients with RI, degree III, with progressive hypoxemia, hypercapnia, MC disorder in all the links. An insignificant positive time course in the state of gas exchange, MC and blood kinins after therapy was indicative of insufficient efficacy of multiple modality therapy and permitted recommendation of drugs correcting disorders in the above systems.     

The antihypertensive efficacy of hydrochlorothiazide is not prostacyclin dependent

We tested the hypothesis that vascular prostacyclin synthesis is stimulated by hydrochlorothiazide and could account for some of the drug's antihypertensive effect. We studied 13 patients with mild essential hypertension in a randomized, double-blind design to assess the effects of indomethacin on hydrochlorothiazide's ability to lower blood pressure, alter body weight, stimulate plasma renin activity, and modulate vascular prostacyclin biosynthesis as assessed by the urinary excretion of the major enzymatically produced metabolite of prostacyclin, 2,3-dinor-6-keto-prostaglandin F1 alpha (PGF1 alpha), measured by GC/MS. Administration of hydrochlorothiazide, 50 mg daily for 2 weeks, was associated with a significant decrease in both systolic and diastolic blood pressure in both supine (systolic, 148 +/- 3 to 136 +/- 3 mm Hg; diastolic, 97 +/- 2 to 94 +/- 3 mm Hg) and upright (systolic, 151 +/- 4 to 131 +/- 2 mm Hg; diastolic, 103 +/- 2 to 97 +/- 3 mm Hg) positions. Hydrochlorothiazide administration resulted in a 1 kg weight loss and stimulation of plasma renin activity from 1.7 +/- 0.4 to 5.3 +/- 1.1 ng angiotensin I/ml/hr. However, the urinary excretion of 2,3-dinor-6-keto-PGF1 alpha was unchanged after administration of hydrochlorothiazide (86 +/- 13/ng/gm creatinine during placebo, 74 +/- 13 ng/gm during week 1 of hydrochlorothiazide, and 70 +/- 9 ng/gm during week 2 of the drug). Administration of indomethacin, 50 mg twice a day, resulted in greater than 60% inhibition of 2,3-dinor-6-keto-PGF1 alpha excretion but did not affect the antihypertensive response to hydrochlorothiazide. Indomethacin did not oppose the diuretic effect of hydrochlorothiazide as assessed by weight loss but did attenuate the rise in plasma renin activity. Our data demonstrate that the blood pressure-lowering effect of a thiazide diuretic does not require enhanced prostacyclin synthesis and the cyclooxygenase inhibitor indomethacin does not antagonize the antihypertensive efficacy of hydrochlorothiazide.     

Vascular remodeling and the kallikrein-kinin system

Remodeling of the arterial wall occurs mainly as a consequence of increased wall stress caused by hypertension. In this issue of the JCI, Azizi et al. report that in humans with a kallikrein gene polymorphism that lowers kallikrein activity, the brachial artery undergoes eutrophic inward remodeling in the absence of hypertension or other hemodynamic changes. It has also been reported that alterations of the kallikrein-kinin system are associated with formation of aortic aneurysms. Conversely, after vascular injury, kinins mediate the beneficial effect of angiotensin-converting enzyme inhibitors that prevent neointima formation. These findings raise the intriguing possibility that decreased kallikrein-kinin system activity may play an important role in the pathogenesis of vascular remodeling and disease, while increased activity may have a beneficial effect.     

Examination of the molecular diversity of alpha1 antitrypsin in urine: deficit of an alpha1 globulin fraction on cellulose acetate membrane electrophoresis

In the clinical field of nephrology, a noninvasive approach employing the analysis of electrophoretic patterns in urinary protein has been established. In this study a total of 52 urine samples with IgA nephropathy (IgAN), anti-neutrophil cytoplasmic antigen-associated crescentic glomerulonephritis (GN), and other types of GN were analyzed. Patients with high alpha1 globulin (alpha1G) fractions, which contained alpha1AT in cellulose acetate membrane electrophoresis (CAE), tended to have alpha1 antitrypsin (alpha1AT) of normal molecular weight (57 kDa and 49 kDa), while patients with a deficit alpha1G fraction tended to have alpha1AT of low molecular weight (<49 kDa) (P < 0.01). The alpha1G fraction was significantly higher in patients with IgAN, and there were significantly more patients with normal molecular weight alpha1AT compared to patients with other diseases (P < 0.01). The isoelectric point of alpha1AT with lower-weight molecules was more on the alkali side compared to higher-weight molecules in two-dimensional electrophoresis. Detecting changes in alpha1G fractions in CAE may support the differential diagnosis of IgAN from other types of GN.     

Hypertension in Dahl salt-sensitive rats: biochemical and immunohistochemical studies.

1. The renin-angiotensin and kinin-kallikrein systems of Dahl salt-sensitive and salt-resistant rats fed diets with different salt contents were analysed using biochemical and immunocytochemical techniques. 2. Blood pressure increased by 45% in salt-sensitive rats only, after 4 weeks on a high-salt diet. The plasma renin activity and plasma angiotensin II concentration remained at the same levels in salt-sensitive rats on the high-salt diet as on the normal salt diet, whereas the plasma renin activity and plasma angiotensin II concentration of salt-resistant rats fed the high-salt diet were lower. The plasma renin activity and the plasma angiotensin II concentration were elevated in both salt-resistant and salt-sensitive rats fed the salt-deficient diet but were much more elevated in salt-resistant than in salt-sensitive rats. 3. The kidney immunocytochemical data paralleled the data on plasma parameters. Salt-sensitive rats had fewer renin positive juxtaglomerular apparatuses than salt-resistant rats on the normal diet, and the increase on the sodium-deficient diet was also smaller in salt-sensitive rats. Salt-sensitive rats fed the high-salt diet and the standard diet had almost no angiotensin II immunoreactivity compared with the salt-resistant rats on the same diets. 4. The total renal kallikrein content of salt-sensitive rats was lower than that of salt-resistant rats on all three diets, as was the amount of kallikrein excreted in the urine on the standard and the high-salt diets. The differences resulted from a reduction in active kallikrein. The increase in kallikrein in salt-sensitive and salt-resistant rats on the salt-deficient diet was not significantly different. 5. There were similar changes in immunopositive kallikrein in the kidneys of salt-sensitive and salt-resistant rats with diet, with a large increase in kallikrein biosynthesis on the low-salt diet. The plasma concentration of high-molecular-mass kininogen was not significantly different in salt-sensitive and salt-resistant rats, but there was a significant increase in T-kininogen in salt-sensitive rats fed the high-salt diet. 6. In conclusion, the absence of decreases in the plasma renin activity and the plasma angiotensin II concentration in salt-sensitive rats fed the high-salt diet might partially explain the increase in blood pressure.     

Effects of clonidine and guanfacine in essential hypertension

Daily doses of 0.3 mg clonidine and 3 mg guanfacine were equiactive in decreasing blood pressure and heart rate in 17 subjects with essential hypertension. Clonidine decreased cardiac output and guanfacine decreased total peripheral resistance, while clonidine had no effect on stroke volume but guanfacine increased it. Both clonidine and guanfacine decreased plasma renin activity. Naloxone, 0.4 mg iv, reversed the antihypertensive effect of clonidine but was ineffective even at higher doses (1.6 mg iv) when subjects were treated with placebo or guanfacine. It is suggested that the hemodynamic differences between the two centrally acting alpha 2-adrenoceptor agonist antihypertensive drugs may at least in part result from the involvement of opioid mechanisms only in the action of clonidine.     

Prorenin-renin conversion by the contact activation system in human plasma: role of plasma protease inhibitors

Acid-pretreated normal human plasma generates renin activity at 0 degree C and neutral pH by the activation of prorenin. The activation is caused by kallikrein generated from prekallikrein by activated factor XII. Nonacidified plasma also generates renin at 0 degree C, but at a lower rate (cold-promoted activation). In normal plasma, 14% +/- 1% of prorenin (mean +/- SEM, n = 30) was activated during incubation at 0 degree C for 7 days (range 6% to 26%). Cold-promoted activation of prorenin was within the normal range in plasma deficient in factor XI, X, IX, VIIIC, VII, V, prothrombin, or high mol wt kininogen. Cold-promoted activation of prorenin was less than or equal to 1% in plasma deficient in factor XII or prekallikrein. Reconstitution of these plasmas with highly purified factor XII or prekallikrein restored normal prorenin activation. Correction of high mol wt kininogen deficiency had no effect. Thus cold-promoted activation of prorenin depends on the presence of factor XII and prekallikrein, whereas the other clotting factors are not essential. The influence of the inhibitors C1 esterase-inhibitor, alpha 2-macroglobulin, antithrombin III, and alpha 1-antitrypsin on the activation of prorenin was studied in factor XII-deficient plasma from which one or more of these inhibitors had been selectively removed by immunoadsorption. Factor XII was subsequently added, and the generation of renin at 37 degrees C was observed after complete factor XII-high mol wt kininogen-mediated activation of prekallikrein induced by dextran sulfate. No activation of prorenin was observed at 37 degrees C after depletion of C1 esterase inhibitor, alpha 2-macroglobulin, antithrombin III, or alpha 1-antitrypsin. When prekallikrein was activated in plasma depleted of both C1 esterase-inhibitor and alpha 2-macroglobulin, 6% of prorenin was activated in 2 hours at 37 degrees C. After additional depletion of antithrombin III, the activation increased to 47%. These results indicate that the contact activation system is capable of activating prorenin in plasma at physiologic pH and temperature when the three most important kallikrein inhibitors, C1 esterase-inhibitor, alpha 2-macroglobulin, and antithrombin III, are absent.     

Metoclopramide and domperidone block the antihypertensive effect of bromocriptine in hypertensive patients

This study was conducted in normotensive and hypertensive subjects at the Vargas Hospital of Caracas. Normotensive subjects received, in a cross-over fashion, placebo, metoclopramide (MTC), or domperidone (DOMP), 40 mg of each drug, daily for 1 week. The first group of patients under placebo for 1 week received a single 2.5-mg oral dose of bromocriptine (Br). The second group of patients received 30 mg MTC daily (divided into three doses) for 1 week. At the end of the period a single dose of 2.5 mg Br was administered to each patient. The third group of eight hypertensive patients received DOMP for 1 week at 30 mg/d and then a single 2.5-mg Br dose. Cardiovascular and biochemical parameters including arterial pressure, heart rate, plasma renin activity, and plasma aldosterone were evaluated during the 6-hour period before and after the administration of Br. Neither DOMP nor MTC significantly modified blood pressure and heart rate in normotensive patients. Br reduced both systolic and diastolic arterial pressure in hypertensive subjects. The peak of the antihypertensive effect appeared 3 hours after drug administration, but reduction of arterial pressure lasted approximately 6 hours. At the same time, Br reduced plasma aldosterone levels and plasma renin activity. MTC and DOMP reversed the antihypertensive effect of Br and its effect on aldosterone levels and plasma renin activity. We conclude from these findings that Br acts as an antihypertensive agent at peripheral and central levels by stimulating dopamine-2 receptors, which are involved in the aldosterone and renin secretion.     

Studies on the prekallikrein (kallikreinogen)-kallikrein enzyme system of human plasma: I. Isolation and purification of plasma kallikreins

By measurement of its arginine esterase activity, plasma kallikrein was purified from fresh frozen ACD plasma. The steps involved alcohol fractionation, isoelectric precipitation, and carboxymethyl (CM) Sephadex and DEAE cellulose chromatography. Three enzymatically active fractions were finally isolated and termed plasma kallikreins I, II, and III; they represented purifications of 970,320- and 590-fold, respectively. All three kallikreins were active biologically; they increased vascular permeability in the guinea pig and released a kinin from human plasma, as measured in the rat uterus bioassay. Bradykinin and/or closely related kinins were identified in the kallikrein I plasma digest by radioimmunoassay.Kallikreins I, II, and III had similar ratios of hydrolytic activity on a variety of arginine and lysine esters and were immunochemically related. However, differences were present on physicochemical characterization: kallikrein I had S(20,[unk]) of 5.7, a mol wt of 99,800, and migrated as a slow gamma globulin; kallikrein II migrated as a fast gamma globulin with a mol wt of 163,000, but the evidence suggested that it was closely related, if not interconvertible, with kallikrein I. Kallikrein III, on the other hand, migrated as an alpha globulin and reacted quite differently with inhibitors.     

The activity of the components of the kinin system in renal vein blood in vasorenal arterial hypertension]

Fifty-four patients with vasorenal arterial hypertension were examined for the activity of kallikrein, prekallikrein, carboxycatepsin and renin in the blood of renal veins. In patients with an appreciable stenosing of one of renal arteries, asymmetry of kallikrein excretion due to its activity reduction was discovered on the side of the ischemized kidney. In patients with unilateral insignificant stenosis of the renal artery and bilateral stenosing of renal arteries, no consistent asymmetry in the activity of the enzymes under study was revealed.