Active immunization against renin in normotensive marmoset.

Primate renins (human and monkey) are very similar. We used pure human renin to immunize marmosets (Callithrix jacchus) and thereby produce a chronic blockade of the renin-angiotensinogen reaction. After a control period of 2 months, five male marmosets, on their usual sodium-poor diet, were immunized against pure human renin by three subcutaneous injections of 30 micrograms each, with complete and then incomplete Freund's adjuvant. Three marmosets were injected with adjuvant only and served as controls. Blood sampling and blood pressure measurements were performed weekly. After the third injection, the five marmosets immunized against renin developed a high titer of renin antibodies (50% binding of 125I-labeled human renin at a dilution of greater than or equal to 1:10,000). The antibodies inhibited the enzymatic activity of both marmoset and human renins. At the same time, systolic blood pressure decreased significantly from 125 +/- 13 mm Hg to 87 +/- 8 mm Hg (mean +/- SD; 1 mm Hg = 133 Pa). Plasma renin enzyme activity was undetectable in three animals. Plasma aldosterone decreased significantly. After 1-4 months with low blood pressure, a normal urinary output, and a normal plasma creatinine, the five marmosets became sick and died within one month. At autopsy an immunological renal disease, characterized by the presence of immunoglobulin and macrophage infiltration colocalized with renin, was found. Granulomatous formations, probably due to Freund's adjuvant, could be seen in the lungs and in the kidney. No immunoglobulin was detectable in extrarenal vessels or in other organs. These experiments demonstrate that, in this primate, a chronic blockade of the renin-angiotensin system can be achieved by active immunization against homologous renin, but this blockade is associated with the development of an autoimmune disease localized in the kidney.     

Cardiac reflexes in normotensive and spontaneously hypertensive rats.

Characteristics of left atrial receptors were studied in normotensive control (Wistar) and spontenaously hypertensive rats. The left atrial pressure was chronically elevated in spontaneously hypertensive rats and at the end of the expiratory phase was 10.3 mm Hg as compared with 4.6 mm Hg in normotensive control rats. The thresholds of the receptor endings were twice as high in the hypertensive as in the normotensive rats (10.2 and 4.6 mm Hg, respectively). In other experiments the reflex inhibition of renal sympathetic outflow was studied during plasma infusion in baroreceptor denervated normotensive and hypertensive rats was was inhibited at a lower left atrial pressure in the former. These differences are attirubted to decreased distensibility of the left atrium in spotaneously hypertensive rats. The reflex splanchnic nerve inhibition with volume load also was recorded in awake rats. At a 10 percent increase in blood volume, splanchnic outflow was more significantly decreased in spotaneously hypertensive than in normotensive rats. The mechanism underlying such a hyperreactive volume receptor response is unknown, but a less distensible venous system, centrally or peripherally, might be a contributing factor.     

Calcitonin gene-related peptide in normotensive and spontaneously hypertensive rats

Using specific radioimmunoassay, radioimmunoreceptor analysis and gel filtration, we found that calcitonin gene-related peptides (CGRP) were distributed in various tissues of normotensive rat (WKY) and spontaneously hypertensive rat (SHR), the highest content was in the lumbar spinal cord (1197 +/- 94.8 pg/mg tissue), the lowest in the auricle (15.0 +/- 2.1 pg/mg tissue). Compared with WKY, the plasma CGRP concentration decreased and the CGRP content in abdominal aorta and hypothalamus increased in SHR. By gel filtration, it showed that only one major molecular form of CGRP was present in the tissues. The CGRP specific binding sites were present both in SHR and WKY hearts, but the number of CGRP binding sites in SHR heart was higher and the binding affinity lower than those in WKY heart. Besides, CGRP can reduce the mean arterial pressure (MAP) in the SHR in a dose-dependent way. The above data indicated that CGRP may play an important role in the pathogenesis of hypertension and exert possibly a therapeutic effect on hypertension.     

Kidney renin gene expression in spontaneously hypertensive rats

We studied the expression of kidney renin gene in hypertensive animals by measuring the kidney renin messenger (m) RNA. The kidney renin mRNA was quantified by densitometric Northern blot analysis using a 32P-labelled rat renin genomic DNA fragment as a hybridization probe. Spontaneously hypertensive rats (SHR) and control Wistar-Kyoto rats (WKY) were treated with a low-sodium diet plus furosemide, captopril or propranolol for a week. Plasma renin activity (PRA) in SHR and WKY was increased similarly by sodium depletion and by treatment with captopril. PRA in both strains was not decreased significantly by treatment with propranolol. Both sodium depletion and captopril treatment caused significant increases in the kidney renin mRNA in SHR and WKY. However, the increases in the kidney renin mRNA of SHR were greater than those in the corresponding WKY (SHR, 10.0- and 22.1-fold increases; WKY, 6.2- and 7.8-fold increases, respectively). Propranolol had no effect on the kidney renin gene expression in either WKY or SHR. These results indicate that SHR show an enhanced expression of the renin gene in the kidney compared with WKY in response to stimuli that increase renin release.     

Osmotic regulation of vasopressin and renin in spontaneously hypertensive rats

Abnormalities in the vasopressin and renin systems have been reported in spontaneously hypertensive rats (SHR). Therefore, studies were performed to evaluate the responsiveness of these systems to changes in plasma osmolality and sodium concentration. These variables were manipulated in vivo by intraperitoneal administration of distilled water, isotonic saline, or hypertonic saline to 8- and 18-week-old SHR and normotensive Wistar-Kyoto rats (WKY). Animals were decapitated 30 minutes later, and trunk blood was collected. The hypertonic saline injections resulted in an increase in plasma osmolality and serum sodium at both ages (p less than 0.001). Serum vasopressin was higher in all groups of animals receiving hypertonic saline (1200 mosm/kg H2O; p less than 0.05), but the magnitude of increase was not significantly different in the SHR and WKY at either age. Serum renin activity was lower in SHR than in WKY following acute decreases in serum sodium at 8 weeks, but it was the same for both strains at 18 weeks. Both kidney renin content and concentration were lower in SHR than in WKY at 18 weeks but not at 8 weeks. Therefore, the suppressed renin response to acute osmotic challenge in 8-week-old SHR is not the consequence of reduced kidney renin content. The vasopressin response to osmotic stimulation also was evaluated in vitro using hypothalamoneurohypophyseal explants obtained from 5-, 8-, and 18-week-old SHR and WKY.(ABSTRACT TRUNCATED AT 250 WORDS)     

AT1受体胞外肽段ATR12181主动免疫对SHR心脏的保护作用

目的观察大鼠血管紧张素Ⅱ受体1型(AT1受体)胞外肽段ATR12181主动免疫自发高血压大鼠(SHR)对大鼠心脏是否具有保护作用,并与氯沙坦比较.方法根据大鼠AT1受体胞外肽段氨基酸序列设计ATR12181,合成纯化并与破伤风类毒素耦联.SHR随机分组(1)ATR12181组(n=7)给予ATR12181皮下注射,主动免疫6次;氯沙坦组(n=7)给予氯沙坦(10m·kg-1·d-1)灌胃;(2)对照组(n=7)皮下注射盐水.实验期间动态监测SHR的收缩压及血清抗体滴度.在第24周末,处死动物取心脏组织测量心脏体重比、左室体重比,对心肌组织进行光镜及电镜下形态观察,并检测心肌组织c-fos与AT1受体mRNA水平.结果20周末,ATR12181组抗ATR12181滴度达到3500±400,收缩压为(145.4±8.5)mmHg,显著低于对照组[(197.0±7.7)mmHg,P＜0.05];氯沙坦组收缩压为(139.3±17.2)mmHg也显著低于对照组(P＜0.05).24周末,ATR12181组与氯沙坦组的心脏体重均显著低于对照组(P＜0.05);ATR12181组与氯沙坦组左室体重比也均显著低于对照组(P＜0.05).HE染色结果显示与对照组相比,ATR12181组与氯沙坦组左室组织,心肌细胞肥大减轻,肌纤维排列整齐,心肌间质增生不明显.电镜下ATR12181组与氯沙坦组超微病理变化也较对照组减轻;此外,ATR12181组c-fosmRNA与AT1受体mRNA水平均明显低于对照组(P＜0.05);氯沙坦组c-fosmRNA与AT1受体mRNA水平也均明显低于对照组(P＜0.05).结论AT1受体细胞外多肽片段ATR12181主动免疫SHR能够产生高滴度抗AT1受体的自身抗体,此抗体是阻滞性抗体,能够作用于AT1受体,使得血压下降;该抗体作用于心脏,能够减轻心肌的病理重塑;ATR12181主动免疫对SHR高血压治疗效果不亚于氯沙坦.     

alpha-Adrenergic receptors in cerebral microvessels of normotensive and spontaneously hypertensive rats

In rat cerebral microvessels, we characterized alpha 1- and alpha 2-adrenergic receptors, using [3H]prazosin and [3H]-p-amino-clonidine as radioligands. [3H]Prazosin binding to the cerebral microvessels was saturable and of high affinity (dissociation constant of 78 pM), with a maximum binding of 48 fmol/mg protein. [3H]Prazosin binding reached equilibrium within 15 minutes and was dissociated by the addition of 10 microM phentolamine. The inhibitory effects of isomers of norepinephrine and epinephrine on the binding showed that l-isomers were over 10 times more potent than d-isomers. [3H]-p-Amino-clonidine binding to the cerebral microvessels was saturable and of high affinity (KD = 0.61 nM) with a Bmax of 73 fmol/mg protein. The binding reached equilibrium within 30 minutes, and was dissociated by the addition of 100 microM l-norepinephrine. l-Isomers of norepinephrine and epinephrine were over 10 times more potent than d-isomers in displacing the binding. Thus, both [3H]prazosin and [3H]-p-amino-clonidine bindings to the cerebral microvessels were characterized by saturability, high affinity, reversibility, and stereo-specificity. Furthermore, the specificity of both binding sites was pharmacologically evaluated by the inhibitory effects of various adrenergic agonists and antagonists on the bindings. These data indicate the existence of alpha-adrenergic receptors in the cerebral microvessels and are consistent with the hypothesis that the cerebral microcirculation is regulated by adrenergic innervation. Furthermore, the receptors were measured in cerebral microvessels of spontaneously hypertensive rats and Wistar-Kyoto controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ischemic preconditioning maintains cardioprotection in aging normotensive and spontaneously hypertensive rats

We determined whether ischemic preconditioning could reduce infarct size and improve cardiac function in both aging normotensive Wistar–Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). The left anterior descending coronary artery was occluded for 1 h followed by 3 h reperfusion in aging (∼16 months old) SHR rats and age-matched WKY rats. Hearts were either preconditioned or not (control group) prior to 1 h of coronary artery occlusion. The preconditioning regimen consisted of three cycles of 3 min occlusion followed by 5 min reperfusion applied prior to the subsequent 1 h occlusion. In WKY (n = 12 each group), the risk zone was similar in the control (51 ± 2%) and preconditioned group (46 ± 2%; p = 0.1). Preconditioning significantly reduced infarct size (as a percentage of the ischemic risk zone) (24 ± 6%) compared to controls (51 ± 5%; p = 0.0026). In SHR rats (n = 9 each group), the risk zone was smaller in the preconditioning group (41 ± 3%) than in the control group (51 ± 3%; p = 0.035). Infarct size (as % of ischemic risk zone) was also significantly reduced in the preconditioned group (13 ± 4%) compared to controls (62 ± 5%; p < 0.0001). For both WKY and SHR rats, for any sized risk zone the infarct size was smaller in preconditioned hearts compared with the control hearts. Preconditioning improved aspects of LV function during ischemia and reperfusion phase in SHR rats, but these benefits were not observed in the WKY rats. Preconditioning maintains powerful cardioprotection in aging normotensive hearts as well as aging hypertrophied hearts.     

Blood pressure and salt appetite of cross-suckled spontaneously hypertensive and normotensive rats

An examination has been made of the blood pressure (BP), saline preference and circulating renin-angiotensin system of spontaneously hypertensive rats (SHR) of the Okamoto strain, normotensive Sprague-Dawley (SD) rats, SHR suckled from immediately after birth on an SD foster mother (SHR-on-SD) and SD cross-suckled on an SHR foster mother (SD-on-SHR). While the BP of SD-on-SHR was not significantly different from that of control SD, SHR-on-SD had significantly lower BP than SHR suckled on their natural mothers. In two-bottle preference tests, neither the saline preference nor total fluid intake of cross-suckled SHR was significantly different from that of SHR controls. While the total fluid intake of SD-on-SHR was not different from that of SD controls, the saline preference of cross-suckled SD was significantly lower than that of control SD. The heart, adrenal and kidney weights of SHR were significantly greater than those of SD, but there were no significant differences between cross-suckled rats and their respective controls. There were no significant differences in plasma renin activity (PRA) or angiotensin converting enzyme (ACE) activity between any groups and these variables did not correlate with each other, with BP or with saline preference. Thus, some factor transferred from the SHR mother postnatally is required for full expression of the elevated BP, but not the exaggerated saline preference of the SHR. Conversely, the saline preference of SD, but not the BP, is altered by cross-suckling.     

Central actions of atrial natriuretic polypeptides in spontaneously hypertensive and normotensive rats

The effects of intracerebroventricular (i.c.v.) administration of ANP on blood pressure and intakes of water and salt were examined, using conscious, unrestrained normotensive Wistar rats and spontaneously hypertensive rats (SHR). In normotensive rats, i.c.v. administration of alpha-rat ANP (alpha-rANP), alpha-human ANP (alpha-hANP), alpha-rANP (4-28) and alpha-rANP (5-28) at the dose of 1.5 nmol significantly attenuated water intake induced by i.c.v. injection of 0.1 nmol of angiotensin II (AII). Centrally administered alpha-hANP (5 micrograms) also attenuated AII-induced pressor response. Centrally injected alpha-hANP (1 microgram) produced a greater reduction of water intake after 24-hour water deprivation in SHR compared to control Wistar Kyoto rats (WKY). Central infusion of alpha-hANP for 1 week also reduced the salt appetite of SHR, as shown by two bottle preference test with 0.3 M NaCl solution and tap water, while it had no effect on drinking behavior of WKY. These results suggest the central antagonistic relationship of the ANP and renin-angiotensin systems and the possible involvement of brain ANP in the pathophysiology of genetically hypertensive rats.     

Acute hemodynamic effects of ethanol in conscious spontaneously hypertensive and normotensive rats

This study investigated the differential hemodynamic effects of small to high doses of ethanol in conscious age-matched spontaneously hypertensive rats (SHRs) and Wistar Kyoto rats (WKYs). Changes evoked by ethanol (0.25, 0.5, or 1 g/kg, i.v.) or equal volume of saline in mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), stroke volume (SV), and total peripheral resistance (TPR) were followed for 90 min in the two rat strains. The baseline MAP (163 +/- 4 vs. 113 +/- 2 mm Hg) of SHRs was significantly (p < 0.05) higher, compared with WKYs due mainly to the presence of an elevated TPR 13.82 +/- 0.12 vs. 2.51 +/- 0.09 mm Hg/ml/min/100 g, p < 0.05) in SHRs. In both rat strains, all doses of ethanol produced immediate increases in MAP at 1 min, after which the MAP responses varied and depended on the rat strain and dose of ethanol used. In WKYs, 0.25 g/kg ethanol had no effect on MAP, but caused significant decreases in CO and SV and increased HR. Ethanol (0.5 and 1 g/kg) produced a short-lived (10 min) and dose-related increase in MAP. The higher dose (1 g/kg) of ethanol elicited significant (p < 0.05) increases in TPR that were counterbalanced by concomitant decreases in CO and SV. In SHRs, the two higher doses (0.5 and 1 g/kg) of ethanol elicited significant (p < 0.05) decreases and increases in MAP, respectively, compared with control (saline-treated) values. The pressor response to the 1 g/kg dose of ethanol was associated with an increase in TPR that achieved a statistical significance (p < 0.05) at 50 and 80 min after ethanol administration. HR was significantly (p < 0.05) reduced by the two higher doses of ethanol, whereas SV and CO were not changed. Blood ethanol concentrations measured 10, 30, and 60 min after ethanol administration were similar in SHRs and WKYs. These findings suggest that acute administration of ethanol to conscious rats elicits hemodynamic responses that are strain- and dose-dependent. In contrast to a short-lived and dose-related pressor response in WKYs, ethanol (0.5 and 1 g/kg) elicited opposite and longer lasting effects on MAP (decreases and increases, respectively) in SHRs. In both rat strains, the pressor response to the higher dose of ethanol was associated with an increase in TPR; an effect that was compromised by a concomitant decrease in CO in WKYs but not SHRs.     

Capillary pressure gradients in cremaster muscle of normotensive and spontaneously hypertensive rats

The purpose of this investigation is to test the hypothesis that capillary pressure gradients are elevated in spontaneously hypertensive rats (SHR) and to determine the mechanism for the elevation. The cremaster muscle was prepared for microscopic examination under chloralose-urethane anesthesia in seven SHR and eight Wistar-Kyoto (WKY) rats 4-6 weeks of age. Capillary hematocrit, diameter, and red cell velocity were measured. Capillary flow induced by a time-varying pressure gradient was treated mathematically. A finite Hankel transformation was applied to the Navier-Stokes equation for capillary vessels. The solution was expressed as a Fourier-Bessel series, and the fluctuation of capillary flow induced by a time-varying pressure gradient was studied. It was shown that if the velocity fluctuation depended only on the pressure gradient, then the velocity fluctuation would be diminished almost instantly after the capillary started to flow. Capillary pressure gradient and shear stress were evaluated according to two different flow models, Newtonian and Casson. The capillary viscosity was obtained from the capillary hematocrit based on the empirical correlation of viscosity vs hematocrit. Calculations based on both flow models indicate that the capillary pressure gradient and shear stress of SHR is higher than in WKY, especially in vessels near 6 microns in diameter. The elevated pressure gradient is due to a combination of reduced capillary density, causing a higher red cell velocity and a tendency toward smaller capillary diameters in the SHR. Capillary hematocrit and viscosity were not elevated in the SHR.     

The vascular response of spontaneously hypertensive and normotensive rats with diabetes mellitus

Streptozotocin-induced diabetes caused an increase in AP and reactivity to noradrenaline in perfused caudal artery of normotensive rats (WKY). In spontaneously hypertensive rats (SHR) diabetes led to an increase in reactivity not only to noradrenaline but also to alpha 1-agonist phenylephrine; a response to endothelium-dependent agent acetylcholine was decreased. Alterations in function of the vascular endothelium may be one of the factors causing elevation of vasoconstriction in diabetes mellitus.     

A comparative study of cardiac function in transgenic hypertensive rats, in spontaneously hypertensive rats and in normotensive rats

Left ventricular hypertrophy (LVH) entails numerous functional and molecular changes that ultimately lead to cardiac insufficiency. The renin-angiotensin system and adrenergic receptor signalling pathway have both been implicated in LVH progression and interactions between these factors may precipitate contractile dysfunction. We therefore investigated cardiac function in hypertensive rats transgenic for the human renin and angiotensinogen genes (TGR) having a genetic activation of the renin-angiotensin system, stroke-prone spontaneously hypertensive rats (SHR) and normotensive controls (CTR) aged 6 weeks. The isolated perfused heart model was used and the effect of isoproterenol (0.1-1000 nmol/L on cardiac function was studied. Cardiac protein and gene expression was studied by Western blot and RNase protection assay. TGR had 75 mmHg higher blood pressure and a 24% higher cardiac/body weight ratio than CTR; blood pressure in SHR was 17 mmHg higher without heart weight difference (p < 0.05). Basal Pmax, +dP/dt and -dP/dt were higher in TGR and SHR compared with CTR hearts. Isoproterenol stimulated these parameters by a maximum factor 6-8 in CTR and SHR but had almost no effect in TGR (p < 0.05). Basal CF per g heart weight was similar in all experimental groups. Isoproterenol produced a significantly smaller vasodilation in TGR compared with CTR or SHR. beta 1 and beta 2 receptor and Gs alpha proteins were similar in TGR, SHR and CTR. Gi alpha was increased in TGR hearts (p < 0.05). Converting enzyme and atrial natriuretic factor mRNA expression was increased (p < 0.01) while beta 1 receptor, adenylyl-cyclase V, SERCA2a and phospholamban mRNA expression was unchanged in TGR compared with CTR. Thus, LVH in TGR is characterised by early adrenergic dysfunction and beta 1 receptor signalling abnormalities indicating progressive functional deterioration. The data may serve as support for an early preventive intervention in angiotensin-II dependent cardiac hypertrophy and may have also implications for patients with genetic alterations of the renin-angiotensin system.     

Hepatic arteries in normotensive and spontaneously hypertensive rats. A morphometric study

The media thickness (m), luminal radius (r) and m/r ratio were determined in the hepatic arterial trunk and in intra-hepatic arterial branches as was the number of arteries per cm2 sectioned liver tissue in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto controls (WKY). The cross-sectional vessel parameters were calculated for a standardized condition, in which the internal elastic membrane is smooth and circular. Both intra-hepatic arterial branches and the hepatic arterial trunk showed significantly higher m/r ratios in SHR than in WKY controls. The luminal radius of the hepatic arterial trunk was larger in SHR than in WKY (P less than 0.05). The number of arteries per cm2 sectioned liver tissue was greater in SHR (P less than 0.05). It is suggested that the consequences of the increased m/r ratio in hepatic arteries of SHR are counteracted to some extent by an increased vascularization, but that during hypovolaemia and compensatory vasoconstriction, a greater decrease in hepatic arterial blood flow occurs in SHR than in WKY.     

Diabetes induced by neonatal streptozotocin treatment in spontaneously hypertensive and normotensive rats

The development of non-insulin-dependent diabetes mellitus (NIDDM) induced by neonatal streptozotocin (STZ) treatment was compared between male spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). The animals were intraperitoneally given 37.5, 50.0, 62.5, or 75.0 mg/kg of STZ at two days of age. At two days after STZ injection, plasma glucose was elevated in both groups of rats according to the dose of STZ, but the level was higher in SHR than in corresponding WKY. At ten days of age, plasma glucose in WKY returned to the similar level to that in vehicle-treated control irrespective of the doses of STZ, while in SHR it remained above control and its level was significantly higher than that in WKY. At 12 weeks of age, plasma glucose was within the control range in WKY, while in SHR it was markedly and dose-dependently elevated. The present study indicates that SHR are susceptible to NIDDM induced by neonatal STZ treatment. The difference in response to STZ between SHR and WKY was discussed.     

Acute effects of captopril on the baroreflex of normotensive and spontaneously hypertensive rats

When captopril was injected intravenously in urethane anesthetized rats, a hypotensive effect accompanied by bradycardia was obtained, while an intravenous (i.v.) injection of prostaglandin I2 (PGI2), which induced hypotension of the same magnitude as the hypotensive effect obtained with captopril, caused a marked tachycardia. Simultaneously, sympathetic nerve activity recorded from abdominal sympathetic nerves was unchanged following injection of captopril, while it was significantly increased during hypotension induced by PGI2. The bradycardia, but not the hypotensive effects induced by captopril was abolished by i.v. pretreatment with atropine. Intracisternal injection of a small dose of captopril inhibited reflex tachycardia during hypotension induced by PGI2 and prolonged the hypotensive effect, while intravenous administration of this dose did not inhibit the reflex tachycardia induced by PGI2. In spontaneously hypertensive rats (SHR), the hypotensive effect of captopril was increased partly, however, the accompanying bradycardia was significantly reduced. These findings suggest that captopril inhibits the baroreflex and centrally activates the cardiac vagal nerve. Moreover in SHR, the effect of captopril on cardiac vagal activity was disturbed.     

Immunisation of spontaneously hypertensive rats against angiotensin I

Immunization against angiotensin I has been considered in comparison with the immunization against renin, in the spontaneously hypertensive rat (SHR). Among 6 different methods of immunization, two (AI-gluta-LPH and AI-Carbo-LPH coupling) permitted to obtain high levels of antibodies against angiotensin I (higher than 1/10,000), after four injections of 50 micrograms AI at three weeks interval. The titration of the antibodies was realized in radio-immuno-assay (RIA), with the determination of the cross-reactivity with AII by the same method. Characterization of the isotypes and the affinity calculation were realized with the ELISA method. The average level of antibodies is about 1/10,000 to 1/100,000, and the cross reactivity of the antibodies for AII is about 0.1 p. 100 in RIA. In ELISA, the study of the different isotypes shows a good maturation of the immune system with a sharp elevation of the IgG1 and IgG2 alpha isotypes, after 2 or 3 injections. The affinity of the antibodies purified by affinity chromatography is about 10.3 10(-9) M. The weekly measure of the arterial pressure during 6 months does not reveal at any moment a fall of pressure during the immunizations. The average pressure of the immunized group (209.4 +/- 23.8 mmHg, n = 40) is non significantly different from the average pressure of the mock group (208.5 +/- 22.6 mmHg, n = 10).     

A major difference of kallikrein-binding protein in spontaneously hypertensive versus normotensive rats

A unique tissue kallikrein-binding protein was identified and partially characterized in the brain and serum of Sprague-Dawley rats and in the serum-free conditioned media of mouse anterior pituitary cells (AtT 20) and rodent neuroblastoma x glioma hybrids (NG108-15). Kallikrein and kallikrein-binding protein(s) form SDS- and heat-stable complexes with a molecular weight (Mr) of approximately 92,000. The complex formation of 125I-labelled kallikrein and the binding protein in the serum and brain is inhibited by excess unlabelled rat urinary kallikrein, rat arginine esterase A (a kallikrein-like kininogenase), and human urinary kallikrein. When the active site of kallikrein was blocked by phenylmethylsulfonyl fluoride or D-Phe-D-Phe-L-Arg-CH2Cl, no complex formation was detected. Kallikrein-binding protein only forms complexes with active kallikrein or trypsin-activated prokallikrein but not with prokallikrein. 125I-labelled kallikrein forms a 92-kilodalton protein with binding protein in various brain regions of perfused normotensive rats of the Wistar-Kyoto strain (WKY), including the cerebral cortex, cerebellum and brain stem; but complex formation was not found in corresponding brain regions of the spontaneously hypertensive rat (SHR). Similarly, the kallikrein-binding protein was identified in various tissues including thymus, lung, liver, prostate, Cowper's gland, adrenal gland, kidney, and pancreas of WKY rats but not in tissues of SHR. The results suggest a major difference in the kallikrein-binding protein in hypertensive versus normotensive rats. The role of this specific kallikrein-binding protein in cellular hemodynamic processes and blood pressure regulation remains to be investigated.