Urinary Kallikrein Research Articles

Effect of magnesium lithospermate B on the renal and urinary kallikrein activities in rats with adenine-induced renal failure.

A study was conducted to examine the effect of magnesium lithospermate B on both the urinary and renal total and active kallikrein and prokallikrein in rats with adenine-induced renal failure. In rats given magnesium lithospermate B at a dose of 10 mg/kg body weight/day for 12 days, significant increases of urinary total and active kallikrein were associated with significant increases of urine volume and urinary total and active kallikrein were associated with significant increases of urine volume and urinary creatinine excretion. The renal total and active kallikrein levels were also significantly elevated by the treatment with magnesium lithospermate B. On day 24, the urinary excretion of total and active kallikrein and prokallikrein was significantly increased. Concomitantly, a significant increase in renal kallikrein (total, active and pro-) was found in the rats given magnesium lithospermate B. A significant relationship existed between the urinary creatinine and active kallikrein excretion. These results suggest that magnesium lithospermate B may stimulate the synthesis of kallikrein and/or conversion to active kallikrein, thus improving renal function.

Hormonal factors influencing fractional excretion of filtered sodium in normal children.

Fractional excretion of filtered sodium (FENa), plasma renin activity (PRA), urinary kallikrein excretion and main urinary metabolite of prostaglandin F2 alpha (PGF MUM) excretion were measured to evaluate the relationship between FENa and these hormonal factors in 33 healthy children aged 8 to 15 years. FENa showed a significant negative correlation with PRA and PGF MUM excretion (P less than 0.001, P less than 0.01, respectively), suggesting that PRA and PGF MUM are useful investigations in evaluating FENa. Especially PRA is often measured routinely and should be measured first, which may provide useful pathophysiological information on the genesis of abnormal FENa.

The kallikrein family of proteins as urinary biomarkers for the detection of prostate cancer

Background Several urinary biomarkers have been assessed as showing a discriminatory ability to differentially diagnose prostate cancer, albeit with manipulation of the prostate. Here we examine the clinical utility of multiple members of the kallikrein family of proteins in non-manipulative urinary biomarker testing. Methods Forty urine samples were collected from patients admitted for urological examination. Twenty, with a confirmed benign diagnosis and 20 with prostate cancer. The levels of 14 kallikrein proteins were measured in patient's urine and normalized for creatinine. Results Ten of the 14 kallikreins tested had detectable levels in urine. However, none showed statistical significance in discriminating patients. Serum PSA was superior to urine PSA and other urinary kallikreins in separating patients with and without prostate cancer. Conclusions We were unable to distinguish men with and without prostate cancer using multiple kallikreins as urinary biomarkers. These results highlight the difficulties in diagnosing prostate cancer via urine testing for soluble biomarkers.

Effects of human urinary tissue kallikreins on vasodilation of basilar artery in rabbits with symptomatic cerebral vasospasm

To evaluate the effects of urinary kallidinogenase on subarachnoid hemorrhage (SAH) in rabbits. Rabbits symptomatic cerebral vasospasm model was built though Endo method, among the 40 rabbits, 8 died or had severe nervous system syndrome, the other 32 were randomly divided into 4 groups:group A, control group, injection of normal saline to the cisterna magna;group B, subarachnoid hemorrhage;group C, injection of human urinary tissue kallikreins;group D, treated with Nimodipine. The behavior scores, neurological scores and cerebral angiography changes were observed. Food intake obviously decreased and neurological deficit were seen in group B, while which were attenuated in group C and group D, and group A was normal. Comparing the diameter of basilar artery was (1.9 +/- 0.3) mm before SAH, the diameter of group B 4 d later was (1.5 +/- 0.3) mm, 7 d later (1.4 +/- 0.3) mm, the difference was significant (P < 0.05). Comparing with group C on the day 4th and 7th, the diameters of basilar artery were significantly different (P < 0.001). Comparing with group D on the day 4th, 7th and 14th, there was no obvious improvement. Urinary kallidinogenase and Nimodipine can obviously alleviate symptomatic cerebral vasospasm in rabbits remarkably, but the former's effect of attenuating vasospasm is better than that of Nimodipine.

Kallikrein genes are associated with lupus and glomerular basement membrane–specific antibody–induced nephritis in mice and humans

Immune-mediated nephritis contributes to disease in systemic lupus erythematosus, Goodpasture syndrome (caused by antibodies specific for glomerular basement membrane [anti-GBM antibodies]), and spontaneous lupus nephritis. Inbred mouse strains differ in susceptibility to anti-GBM antibody-induced and spontaneous lupus nephritis. This study sought to clarify the genetic and molecular factors that maybe responsible for enhanced immune-mediated renal disease in these models. When the kidneys of 3 mouse strains sensitive to anti-GBM antibody-induced nephritis were compared with those of 2 control strains using microarray analysis, one-fifth of the underexpressed genes belonged to the kallikrein gene family,which encodes serine esterases. Mouse strains that upregulated renal and urinary kallikreins exhibited less evidence of disease. Antagonizing the kallikrein pathway augmented disease, while agonists dampened the severity of anti-GBM antibody-induced nephritis. In addition, nephritis-sensitive mouse strains had kallikrein haplotypes that were distinct from those of control strains, including several regulatory polymorphisms,some of which were associated with functional consequences. Indeed, increased susceptibility to anti-GBM antibody-induced nephritis and spontaneous lupus nephritis was achieved by breeding mice with a genetic interval harboring the kallikrein genes onto a disease-resistant background. Finally, both human SLE and spontaneous lupus nephritis were found to be associated with kallikrein genes, particularly KLK1 and the KLK3 promoter, when DNA SNPs from independent cohorts of SLE patients and controls were compared. Collectively, these studies suggest that kallikreins are protective disease-associated genes in anti-GBM antibody-induced nephritis and lupus.

An ATP-sensitive potassium channel blocker suppresses sodium-induced hypertension through increased secretion of urinary kallikrein

It is suggested that an ATP-sensitive potassium channel blocker suppresses sodium-induced hypertension through increased secretion of urinary kallikrein. We reported that glibenclamide, an ATP-sensitive potassium channel blocker, accelerated dose-dependent secretion of renal kallikrein in sliced kidney cortex and in vivo in rats. In vehicle-treated normal Brown- Norway-Kitasato (nBN-Ki) rats, the administration of glibenclamide increased urinary kallikrein secretion, but changed neither the systolic blood pressure nor the urinary sodium on low (0.3%) NaCl diets. Although on high (8%) NaCl diets, the systolic blood pressure of the nBN-Ki rats administrated glibenclamide was significantly lower (P<0.05). The urinary levels of kallikrein and sodium of the nBN-Ki rats administrated glibenclamide were significantly increased (P<0.05, glibenclamide vs. vehicle). A similar result was obtained with a kidney-selective ATP-sensitive potassium blocker, N,N'-dicyclohexyl-4-morpholinecarboxamidine (U18177), in SD rats. Mutant kininogen-deficient Brown-Norway Katholiek (muBN-Ka) rats fed high (8%) NaCl diets showed an increase in urinary kallikrein levels, but showed neither hypotensive nor natriuretic actions by glibenclamide. A bradykinin B(2) receptor antagonist, 8-[3-[N-(E)-3-(6-acetamidopyridin-3-yl) acryloylglyycyl]-N-methylamino]-2,6-dichlorobenzyloxy]-2-methylquinoline (FR173657), which was administrated to SD rats, together with glibenclamide, abolished the hypotensive and natriuretic effects of glibenclamide in high-sodium (8%NaCl) hypertension, despite an accelerated secretion of urinary kallikrein. Therefore, these results indicate that glibenclamide, an ATP-sensitive potassium channel blocker suppressed sodium-induced hypertension through sodium excretion from the kidney resulting from accelerated secretion of urinary kallikrein.

Human urinary kallikrein. Complete amino acid sequence and sites of glycosylation.

Human glandular kallikrein was purified from urine and subjected to detailed structural characterization. The protein was carboxymethylated with iodoacetic acid and digested with TPCK-trypsin, Staphylococcal aureus V-8 protease and endo LysC peptidase. The resulting peptide fragments were separated by reverse-phase HPLC using C-4 columns and acetonitrile-trifluoroacetic acid gradient elution. The complete amino acid sequence of the carboxymethylated derivative was elucidated by sequence analysis and alignment of peptides derived from different proteolytic cleavages. A procedure using in situ CNBr cleavage of a large endo LysC peptidase-derived peptide followed by direct sequencing was carried out to provide overlap for two glycosylation sites at residues 78 and 84. Three Asn-linked glycosylation sites were confirmed by the direct sequence analysis of the isolated glycopeptides. However, the third glycosylation at Asn-144 occurs only in 60% of kallikrein molecules. Reverse-phase HPLC effectively separates two species of HUK which correspond to molecules glycosylated and non-glycosylated at Asn-144, respectively. The human urinary kallikrein contains 238 amino acid residues with Ile and Ser as N- and C-terminal amino acids, respectively. The primary structure is completely identical to that deduced from a human genomic DNA sequence (F.K. Lin et al., manuscript in preparation) and is different in one amino acid (Lys-162 vs. Glu-162) from that deduced from pancreatic or kidney cDNA sequence.

Gonadectomy Influences Blood Pressure through the Kallikrein-Kinin System

The kallikrein-kinin system (KKS) appears to be involved in blood pressure regulation. We showed that ovariectomy (oVx) stimulates urinary kallikrein activity (UKa). So, we test whether gonadectomy (Gx) would affect blood pressure through an increase in KKS activity and which mechanism(s) were involved. We studied adult Wistar rats of either sex, with and without Gx. At baseline all groups were normotensive although the oVx mean arterial pressure (MAP) was lower than female MAP (p < 0.05). KKS blockade by aprotinin increased MAP (p < 0.05) exclusively in the oVx group. The probably mechanism(s) involved in KKS regulation (synthesis, renal content and UKa) were also studied. Previous Gx, kallikrein content (nkat/g kidney weight) and UKa (nkat/g kidney weight/day) were higher in female than in male rats: 12 ± 1.1 versus 6 ± 0.7 and 40 ± 6.8 versus 26 ± 3.4, respectively. After Gx, kallikrein content increased significantly in both orchiectomized (oRx) and oVx rats, and UKa showed a similar tendency (NS). Kallikrein synthesis did not show gender difference in non-Gx rats, but an increase after oVx was observed. KKS was found to be involved in blood pressure regulation in oVx animals. oVx may trigger the increase in kallikrein synthesis and content and UKa to act upon blood pressure.

Are all individuals equally sensitive in the blood pressure to high salt intake?

It has been reported that only one-third of normotensive subjects and half of hypertensive patients are salt-sensitive. Many causes of salt-sensitivity have been proposed. Our suggestion is that a reduced urinary kallikrein level may be one cause, since mutant kininogen-deficient rats, which cannot generate kinin in the urine, are salt-sensitive. Renal kallikrein is secreted by the connecting tubule cells of the kidney, which are located just distal to the macula densa or the tubuloglomerular feedback system. Excess amounts of sodium taken overflow into the distal tubules and are reabsorbed in the collecting ducts. Kinins generated inhibit sodium reabsorption in the collecting ducts. Both blacks and whites with essential hypertension excrete less urinary kallikrein than do their normotensive counterparts, but the mean value in "normotensive blacks" were not different from that in "hypertensive whites". African-Americans consume less potassium than whites. Potassium and ATP-sensitive potassium channel blockers are releasers of renal kallikrein. In a small-scale study, sodium loading caused more increase in the systolic blood pressure in urinary low-kallikrein group than in urinary high-kallikrein group. Large-scale clinical studies, under strict control of potassium intake, are needed to elucidate the relationship between salt-sensitivity and urinary kallikrein levels.

Urinary kallikrein excretion is related to renal function change and inflammatory status in chronic kidney disease patients receiving angiotensin II receptor blocker treatment

This study was to evaluate the correlation of urinary kallikrein to renal function, proteinuria and urinary cytokines in chronic kidney disease patients in a longitudinal follow up. We measured urinary kallikrein and cytokines in 50 patients who were followed up for 12 months. Using regression model we found that the kallikrein excretion (estimated by log kallikrein/creatinine) was positively correlated to log estimated glomerular filtration rate in the beginning and the end of follow up (P = 0.049 and 0.006, respectively). No correlation existed between kallikrein excretion and proteinuria. The kallikrein excretion decreased after 12 months of follow up, which was also associated with the decrease of log estimated glomerular filtration rate. There was a significant positive correlation between the log urinary kallikrein and monocyte chemoattractant protein-1 (MCP-1) concentration (correlation coefficient = 0.277; P = 0.049). Urinary kallikrein excretion was also positively correlated with serum MCP-1 level (correlation coefficient = 0.431; P = 0.002). No correlation existed between urinary kallikrein and transforming growth factor beta-1 or tumour necrosis factor-alpha concentration. Urinary kallikrein excretion is positively correlated to renal function, serum and urinary inflammatory mediator MCP-1 in chronic kidney disease patients. These findings indicate that urinary kallikrein excretion may reflect the change of renal function and kidney inflammatory status.

Urinary Kallikrein and Blood Pressure – Gender-Different Response to Potassium Supplementation in SHR

Aims: To test whether blood pressure is affected by potassium supplementation which modifies urinary kallikrein (UK) in SHR of either sex, and to elucidate the mechanisms involved. Design: In SHR and WKY blood pressure, renal function and hormonal profile were studied after 1% oral potassium supplementation starting at 4 weeks of age and throughout until 12 weeks of age. Results were compared with those of untreated SHR and WKY of either sex. Results: Systolic blood pressure (mm Hg) started to rise in SHR and was significantly different at 6–8 weeks of age: 153.5 ± 7.9 versus 100 ± 5.6 in female and 157 ± 7.7 versus 98.4 ± 6.8 in male rats (p < 0.01). Systolic blood pressure increased progressively in female and male rats reaching 164.5 ± 4.8 and 204.5 ± 7.6, respectively, at 12 weeks of age. At this time systolic blood pressure was higher in male than in female SHR (p < 0.01) and UK activity (UKa; nkat/day/100 g body weight) was slightly lower in male SHR. After 1% oral potassium supplementation administered from 4 to 12 weeks of age, a decrease in systolic blood pressure was seen in male SHR: 204.5 ± 7.6 versus 173.5 ± 7.9 (p < 0.05); and 164.5 ± 4.8 versus 156.8 ± 5.5 in female rats (NS) at 12 weeks of age, concomitant with an increase in UKa, particularly in male rats (29.35 ± 1.92 versus 36.54 ± 2.61, p < 0.05). As expected, plasma aldosterone (pg/ml), increased markedly after potassium treatment from 129 ± 31.4 in untreated female and male SHR and WKY to 528 ± 180.7 in SHR and 473 ± 88.4 in WKY (p < 0.05 in both cases). After potassium supplementation, potassium excretion was significantly correlated with both aldosterone levels and UKa (p < 0.001 in both cases). No significantly concurrent changes in plasma renin activity were observed, but instead a significant decrease was seen in SHR (p < 0.01). The potassium blood pressure-lowering effect was blunted by aldosterone receptor antagonist treatment that also decreased UKa from 36.5 ± 2.61 to 19.5 ± 1.9, particularly in male SHR. No attempt was made in this experimental setting to block kallikrein or kinin receptors. Conclusions: UKa increases as a consequence of aldosterone stimulation by potassium load since an aldosterone receptor blockade abolishes UKa increment and blood pressure fall. These results further support the hypothesis that the kallikrein kinin system plays a role in blood pressure regulation and they also show a gender different response to potassium load in relation to UKa and blood pressure.

Kallikrein gene ‘knock-down’ by small interfering RNA transfection induces a profibrotic phenotype in rat mesangial cells

Emerging evidence suggests that kallikrein exerts renoprotective effects independent of its haemodynamic actions. The aim of the current investigation was to delineate the role of kallikrein in the regulation of fibrosis, by 'knocking down' its expression using specific small interfering RNAs (siRNA). Rat mesangial cells were treated with 12, 60, 120 nmol/l kallikrein-specific siRNAs. The consequent cellular genotypes and phenotypes were analysed. Western blotting demonstrated that mesangial cells produced a kallikrein protein, which was of a different molecular weight to urinary kallikrein from rats of the same species. Treatment of cells with siRNA resulted in a dose-dependent decrease in kallikrein mRNA levels, which impacted on other components of the kallikrein-kinin system, dose-dependently reducing bradykinin B2 receptor mRNA expression. Kallikrein suppression resulted in significant increases in fibronectin and transforming growth factor-beta protein levels in culture supernatants over control levels. Gelatin zymography demonstrated a siRNA dose-dependent decrease in active MMP-2 enzyme levels. Bradykinin, an effector molecule of the kallikrein system, is known to stimulate tissue plasminogen activator production. Paradoxically, however, tissue plasminogen activator protein levels were augmented with increasing kallikrein mRNA silencing. This was accompanied by a dose-dependent decrease in low-density lipoprotein receptor-related protein mRNA levels, indicating that increased tissue plasminogen activator levels were due to an attenuation of receptor-mediated protease clearance. These data lend strong support to the hypothesis that kallikrein exerts antifibrotic, renoprotective effects that are independent of its classical haemodynamic actions.

Pregnant Rats Treated With a Serotonin Precursor Have Reduced Fetal Weight and Lower Plasma Volume and Kallikrein Levels

Pregnant women with preeclampsia have increased serotonin levels, suggesting a possible role of this amine in abnormal pregnancy. With the hypothesis that an increase in serotonin would reduce volume expansion and cause fetal growth restriction, we evaluated the maternal and fetal effects of the administration of the serotonin precursor 5-hidroxytryptophan (5-HTP) to Sprague-Dawley rats. At pregnancy day 13 (n=19) or in random cycle nonpregnant rats (n=10), animals were assigned to a single injection of 5-HTP (100 mg/kg IP) or to a control group. Animals were studied at day 21, after overnight urinary collection. Additional pregnant rats received ketanserin (1 mg/kg), a 5-HT(2) receptor antagonist, 1 hour before 5-HTP injection. In pregnant rats, 5-HTP lowered plasma volume (control: 22+/-1.1; 5-HTP: 17+/-0.7 mL; P<0.001) and creatinine clearance, whereas serum creatinine and urinary protein excretion were increased; no changes were observed in nonpregnant rats. Systolic blood pressure did not change significantly. Urinary kallikrein activity and plasma aldosterone levels decreased only in pregnant animals. Fetal (control: 5.5+/-0.1; 5-HTP: 4.2+/-0.2 g; P<0.001) and placental weights were reduced. In nonpregnant and pregnant animals, 5-HTP caused profound renal morphological alterations and decreased kallikrein immunostaining. Preadministration of ketanserin abolished all of the changes associated with the use of 5-HTP. These data indicate that the administration of a serotonin precursor to pregnant rats limits plasma volume expansion and fetal growth via 5-HT(2) receptors, suggesting a possible role for serotonin in abnormal pregnancy. We postulate that an increased vascular resistance, both at the placental and renal levels, mediates these effects.

Partial Human Genetic Deficiency in Tissue Kallikrein Activity and Renal Calcium Handling

A loss-of-function polymorphism of the human tissue kallikrein (TK) gene (R53H) induces a major decrease in enzyme activity. Inactivation of the TK gene in mice causes a defect in tubular calcium (Ca) reabsorption. Therefore, this study investigated the Ca phenotype of carriers of the 53H allele. In a crossover study, 30 R53R homozygous and 10 R53H heterozygous young white male individuals were randomly assigned to two 7-d low-Ca diets (10 mmol/d) associated with either a low-sodium (Na)/high-potassium (K) diet or a high-Na/low-K diet to modulate TK synthesis. On the seventh day of each diet, the participants were studied before and during a 2-h infusion of furosemide that functionally excludes the thick ascending limb and increases Ca delivery to distal tubular segments. Urinary kallikrein activity was 50 to 60% lower in R53H participants than in R53R participants. Adaptation of urinary Ca excretion to the contrasted Na/K diets was unaffected in R53H participants. By contrast, R53H participants after furosemide infusion had significantly lower serum ionized Ca concentrations than did R53R participants (P < 0.0001) and tendency toward nonsignificantly higher urinary Ca excretions than did R53R participants (P = 0.14). These effects were more marked under low-Na/high-K diet. Despite nonsignificant differences in urinary Ca excretions between the two groups, these results suggest in R53H individuals an increase in Ca reabsorption in the thick ascending limb under baseline conditions that counteracts a distal tubular defect that is revealed by furosemide infusion. In humans as in mice, TK thus may act as an intrarenal modulator of Ca reabsorption.

Growth-stimulating Effect of Kallikrein on Rat Neural Stem Cells-II. Immunocytochemical Analysis and Specificity of the Enzyme for Neural Stem Cells-

In a previous paper we reported a new function of tissue kallikrein: rat urinary kallikrein (RUK) has a marked growth-stimulatory effect on neural stem cells prepared from brains of prenatal rats. We here report that conspicuous differentiation of neural stem cells to neurons and/or glial cells did not occur during stimulation by kallikrein, and this growth-stimulating effect of kallikrein is considerably specific for neural stem cells, i.e., RUK showed no detectable stimulatory effect on rat glial, PC12, GH(3), and HeLa cells. Thus this new function of kallikrein suggests the potential involvement of this enzyme on brain physiology. In addition, this effect of kallikrein for neural stem cells may have value in the treatment of cerebral ischemic stroke-induced injuries etc., i.e., kallikrein administered into the body stimulates neural stem cell proliferation and new neurons may be generated from them.

Renal functional reserve in obesity hypertension

The capacity to increase glomerular filtration rate in response to an acute oral protein load is known as the renal functional reserve; the loss of such capacity is used as a marker of hyperfiltration. This physiological response in obese hypertensives is not yet fully understood. We aimed to study the interdependent effects of obesity and hypertension on renal reserve, taking into account renal kallikrein and nitric oxide in the modulation of that parameter. Fourteen obese hypertensives (mean age, 50.5 +/- 0.9 years) and nine lean hypertensives (mean age, 50.6 +/- 2.7 years) were evaluated. Renal haemodynamics and the levels of serum nitric oxide and urinary kallikrein were assessed at baseline and after a protein load (1 g/kg of body weight). An increase in the following parameters was observed when comparing obese and lean hypertensives: basal glomerular filtration rate; renal plasma flow; and urinary kallikrein and nitric oxide levels (129.2 +/- 2.9 vs. 101.4 +/- 3.4 ml/min/1.73 m2; 587.5 +/- 18.2 vs. 502.8 +/- 16.7 ml/min/1.73 m2; 0.120 +/- 0.02 vs. 0.113 +/- 0.02 mU/ml; 23.2 +/- 0.8 vs. 19.5 +/- 1.2 mmol/ml, respectively). The renal reserve was lower in obese hypertensives when compared with that of lean hypertensives (4.1 +/- 0.5 vs. 11.8 +/- 0.8 ml/min, p < 0.005). After a protein load, contrasting with the lean group, inability to elevate the nitric oxide serum levels and a lower increase in urinary kallikrein were observed in the obese group. These data suggest that obese hypertensives lose renal reserve earlier in the evolution to renal dysfunction. This may be due to the defective modulation of renal vasodilatation mechanisms by renal kallikrein and nitric oxide production.

Effect of Testosterone Administration on Serum and Urine Kallikrein Concentrations in Female-to-Male Transsexuals

Concentrations of human tissue kallikreins (hKs), a group of 15 secreted serine proteases found in many tissues, are modulated by steroid hormones in cancer cell lines. To gain insight into in vivo kallikrein regulation we measured kallikrein concentrations in serum and urinary tissue in female-to-male transsexuals before and after testosterone administration. We collected blood and urine samples before treatment and after 4 and 12 months from 28 female-to-male transsexuals who received 250 mg of testosterone esters intramuscularly every 2 weeks. We used ELISA assays to measure multiple kallikreins in serum and urine. After testosterone administration, serum testosterone concentrations increased by approximately 15-fold. Serum kallikrein concentrations increased dramatically for hK3 (prostate-specific antigen) and increased moderately for hK2, hK5, hK6, hK7, hK8, hK10, and hK11. In urine, we noted major increases for hK3 and hK2 only. For all other kallikrein concentrations, we observed no considerable changes. We conclude that, in serum and urine of female-to-male transsexuals after testosterone administration, hK3 (prostate-specific antigen) and to a lesser extent hK2 concentrations increase dramatically, but concentration of other kallikreins increase either moderately in serum (hK5, hK6, hK7, hK8, hK10, and hK11) or not at all in either serum (hK4, hK13, hK14) or urine (hK4, hK5, hK6, hK7, hK8, hK10, hK11, hK13, hK14).

Effect of Prepuberal Gonadectomy upon Aldosterone Levels in Female and Male SHR: Interaction between Blood Pressure and Kallikrein Kinin System

It has been suggested that an abnormal activity of the hypothalamic-pituitary-adrenal-gonadal axis may be implicated in the pathogenesis of spontaneously hypertensive rats (SHR) blood pressure hypertension. However, it is widely known that the kallikrein-kinin system plays a role in blood pressure regulation in this strain, because an inverse relation between blood pressure and urinary kallikrein excretion has been reported. It was of our interest to study how early suppression of sexual hormones affected blood pressure regulation in SHR and urinary kallikrein excretion and to elucidate the involved mechanisms. For these purpose, SH and Wistar-Kyoto (WKY) rats blood pressure, renal function, and hormonal profile were studied after prepuberal gonadectomy starting at 4 weeks of age throughout until the 12th week of age. Results were compared with those of untreated SH and WKY rats of either sex. The response to blocking agents against aldosterone and kallikrein-kinin system also were evaluated. Systolic blood pressure increased progressively in male and female SHR 12 weeks of age. Systolic blood pressure was higher in male than in female SHR, but urinary kallikrein was lower in male SHR. Prepuberal gonadectomy induced a significant decrease in systolic blood pressure in male and in female SHR at 12 weeks of age, accompanied by an increase in urinary kallikrein in male and in female SHR. Plasma aldosterone increased markedly in female and male SHR after gonadectomy. No concurrent changes in plasma renin activity or corticosterone levels were observed. The aldosterone receptor antagonist and the kallikrein inhibitor treatment blunted the blood pressure lowering effect of gonadectomy and diminished urinary kallikrein excretion. Results support the existence of a sexual dimorphism related to hypertension and urinary kallikrein and suggest an interaction among the kallikrein-kinin system, sexual hormones, and mineralocorticoids in the neonatal programming of hypertension.

A Missing Link Between a High Salt Intake and Blood Pressure Increase

It is widely accepted that a high sodium intake triggers blood pressure rise. However, only one-third of the normotensive subjects were reported to show salt-sensitivity in their blood pressure. Many factors have been proposed as causes of salt-sensitive hypertension, but none of them provides a satisfactory explanation. We propose, on the basis of accumulated data, that the reduced activity of the kallikrein-kinin system in the kidney may provide this link. Renal kallikrein is secreted by the distal connecting tubular cells and all kallikrein-kinin system components are distributed along the collecting ducts in the distal nephron. Bradykinin generated is immediately destroyed by carboxypeptidase Y-like exopeptidase and neutral endopeptidase, both quite independent from the kininases in plasma, such as angiotensin converting enzyme. The salt-sensitivity of the blood pressure depends largely upon ethnicity and potassium intake. Interestingly, potassium and ATP-sensitive potassium (K(ATP)) channel blockers accelerate renal kallikrein secretion and suppress blood pressure rises in animal hypertension models. Measurement of urinary kallikrein may become necessary in salt-sensitive normotensive and hypertensive subjects. Furthermore, pharmaceutical development of renal kallikrein releasers, such as K(ATP) channel blockers, and renal kininase inhibitors, such as ebelactone B, may lead to the development of novel antihypertensive drugs.

Increased activity of plasma and tissue kallikreins, plasma kininase II and salivary kallikrein in pemphigus foliaceus (fogo selvagem)

Pemphigus foliaceus (PF) is an autoimmune blistering disease of unknown aetiology, which is endemic in Brazil. Although the pathogenesis of PF is still unknown, proteins of the contact system have been implicated. As the components of the kinin system may interact with those of the contact system, in this study we evaluated the plasma levels of high-molecular-weight kininogen (HK) and low-molecular-weight kininogen (LK), and the activity of plasma kallikrein, tissue kallikrein and kininase II in plasma of patients with PF presenting with Nikolsky's sign. As kidneys and salivary glands are relevant sources of tissue kallikrein for plasma, we also evaluated urinary/salivary kallikrein and urinary kininase II activities. Fifteen patients and 15 age- and sex-matched controls were studied. Kininogen levels were determined by enzyme-linked immunosorbent assay, and the activities of kallikreins and kininase II were determined using selective chromogenic substrates. Compared with controls, plasma HK levels were decreased (P = 0.031), whereas the activities of plasma kallikrein, tissue kallikrein and kininase II in plasma, and the activity of salivary kallikrein, were increased in patients (P < 0.001 for each comparison). Plasma levels of LK and the activities of urinary kallikrein and urinary kininase II were not significantly different from controls. Diminished levels of HK associated with increased activities of plasma kallikrein and kininase II indicate that the kinin system is activated at the systemic level in PF. As active plasma kallikreins may act on some proteins of the contact system, it is possible that the enzyme may contribute to blister formation. The further observation of an increased tissue kallikrein activity at the systemic and saliva levels may be interpreted as a systemic reflex of skin inflammation. Whether the activation of the kinin system is a cause or a consequence of blister formation needs further clarification.