Relationship of urinary kallikrein excretion to urinary potassium excretion during furosemide administration with and without amiloride

The relationship of urinary kallikrein excretion to urine volume, and to urinary sodium and potassium excretions was studied in normal rats during furosemide diuresis and superimposed injection of amiloride, a K+-sparing diuretic. Continuous infusion of furosemide increased urinary kallikrein, sodium and potassium excretions and the urine volume. Amiloride injection during furosemide diuresis caused further increase in diuresis and natriuresis, but a prompt decrease in urinary kallikrein excretion to basal level, and potassium excretion to below the basal level. The significant correlation of urinary kallikrein excretion to urinary potassium excretion, but not to urine volume and urinary sodium excretion after amiloride injection suggests that the major determinant of urinary kallikrein excretion is renal potassium secretion through a mechanism that is affected by amiloride.     

Acute modifications of extracellular space components and urinary kallikrein excretion

In control rats urinary kallikrein excretion was positively correlated with inulin space and its both components, plasma volume and interstitial space. When the animals were infused with dextrose solution or dextrose albumin solution the distribution of water in extracellular space was altered and the correlations with urinary kallikrein excretion disappear. We conclude that the possible regulation of the components of the extracellular space on urinary kallikrein excretion has not the same importance when water distribution is altered, at least in acute situations.     

Vasopressin stimulates urinary kallikrein excretion in the isolated erythrocyte-perfused rat kidney

We have found that arginine vasopressin (AVP) (10 pg/ml) stimulates urinary kallikrein in the isolated erythrocyte perfused rat kidney. (In this model, perfusate flow rate approximates blood flow rates in vivo and morphology is normal.) Urinary kallikrein excretion rose from 6.9 +/- 0.8 to 14.9 +/- 2.4 ng/min 20 min after the addition of AVP to the perfusate, and then fell towards baseline levels over the next 30 min. 1-Desamino-8-D-AVP (8 pg/ml) caused a comparable increase in kallikrein excretion. Prostaglandin synthesis inhibition with indomethacin did not alter the stimulatory effect of AVP on kallikrein excretion. Parathyroid hormone 1-34 (144 ng/ml) and calcitonin (102 ng/ml) also increased urinary kallikrein. Kallikrein excretion rose from 9.1 +/- 2.0 to 24 +/- 4.5 ng/min in response to calcitonin and from 8.3 +/- 1.6 to 43.7 +/- 3.4 ng/min following the addition of parathyroid hormone to the perfusate. Kallikrein was found to accumulate in the perfusate in a linear fashion. Based on the slope of the relationship between perfusate kallikrein and time, the rate of release of kallikrein into the perfusate was estimated to be 0.79 ng/min in control kidneys. The rate of release of kallikrein into the perfusate in kidneys treated with AVP was the same (0.74 ng/min). Thus while kallikrein is released into the perfusate, this process is not influenced by AVP. In conclusion, AVP stimulates release of kallikrein into the urine (but not the perfusate) independently of systemic events. The effect of AVP is not mediated by prostaglandins. This effect of AVP is mediated via stimulation of the V2 receptor and also occurs in response to two other hormones (calcitonin and parathyroid hormone) that are known to stimulate adenyl cyclase in the rat distal nephron.     

Effects of environmental lead levels on the urinary kallikrein excretion of exposed workers

Ten men, working in a factory making car batteries, were hospitalized in order to establish the diagnosis of lead intoxication. The urinary kallikrein activity, determined in their 24-hr urines, was found to be lower than that of a control group. Kallikrein activity was then determined in morning urines of another group of 25 lead exposed men working in the same factory. The urines of this group were collected before and after some environmental improvements which reduced lead concentration in the factory ambient air. The urinary kallikrein excretion of exposed workers was very low before environmental improvements. After the lead reduction in the environmental air, the urinary kallikrein excretion of the same workers was significantly increased; nevertheless, it remained still lower than the control group.     

Inverse relationship between renal and urinary kallikrein during chromate-induced acute renal failure in rat: urinary kallikrein excretion as a possible recovery index

Acute renal failure (ARF) was induced in rat following a single injection of sodium chromate. A transient polyuria and a 10-fold decrease in glomerular filtration rate was immediately observed after sodium chromate administration. Urinary sodium and potassium excretion were reduced within 24 h and remained decreased for 8 to 10 days. Progressive recovery of normal renal functions, mainly electrolyte excretion and filtration rate was observed 12 days after sodium chromate administration. Urinary kallikrein excretion (UKE) was decreased only 48 h after sodium chromate administration. However the proportion of the active and inactive form excreted was unchanged. UKE remained also at a reduced level for 8 to 10 days and returned progressively to base-line level. The kallikrein content in the tissue was significantly increased immediately after sodium chromate administration and recovered normal values 12 days later. The increase of kallikrein in the tissue is more likely unspecific due to impaired protein transport than a specific stimulation of renal kallikrein biosynthesis. The decreased UKE may indicate a distal tubular reversible dysfunction in this ARF model. These reductions in electrolyte excretion, glomerular filtration and UKE were associated with selective morphological lesions. Whereas the glomeruli were intact, important damages affected proximal tubule cells which appeared necrotic and showed presence of vacuoles, liquefaction of cytoplasmic material and lost of microvilli. Less marked lesions were however observed in distal tubules, particularly large vacuoles were present at the apical poles of the tubule cells, the sites of kallikrein secretion. These distal damages may be involved in the increase of tissue concentration and in the decrease of UKE.(ABSTRACT TRUNCATED AT 250 WORDS)     

Decrease in urinary excretion of active kallikrein in conscious young and adult spontaneously hypertensive rats

Urinary excretion of active kallikrein was determined every day (amidolytic assay) in 6 male Okamoto-Aoki spontaneously hypertensive rats (SHR) and 6 male normotensive Wistar-Kyoto rats (WKY) from ages 4 to 7 weeks and from 12 to 15 weeks. The rats were housed in individual metabolic cages and were allowed free access to food having normal sodium content and to tap water. Urinary kallikrein excretion was lower in 4-week-old SHR than in age-matched WKY (7.8 +/- 1.4 vs. 15.5 +/- 2.3 nkat/24 h respectively, P less than 0.01) at a moment when systolic blood pressure (BP) in SHR was already higher than in WKY. The slope of the increase in active kallikrein excretion from week 4 to 7 was not different for SHR and WKY (6.34 +/- 1.05 vs. 7.50 +/- 1.02 nkat/24 h-1 . wk-1 respectively). In contrast, from week 12 to 15, this slope was not significant for SHR (1.67 +/- 2.55 nkat/24 h-1 . wk-1) while it remained positive in WKY (7.36 +/- 3,44 nkat/24 h-1 . wk-1). In both SHR and WKY, urinary kallikrein excretion was directly related to BP from week 4 to 7 but the slope of the regression line was less for SHR than for WKY (0.19 +/- 0.05 vs. 0.48 +/- 0.12 nkat/24 h-1 . mm Hg respectively). From ages 12 to 15 weeks, kallikrein excretion was still related to pressure in WKY (y = 1.92 x - 180.8; r = 0.93) but not in SHR (y = 0.71 x - 81.48; r = 0.52).(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma renin activity and urinary kallikrein excretion in lead-exposed workers as related to hypertension and nephropathy

Urinary kallikrein activity and plasma renin activity (PRA) in supine and erect positions were determined in 22 men occupationally exposed to lead. In eight of them, suffering from hypertension and/or nephropathy, urinary kallikrein activity was low or absent, while PRA was normal or reduced. The other fourteen non-symptomatic workers showed normal or reduced urinary kallikrein activity and variable PRA. Urinary kallikrein activity of lead-exposed workers was significantly correlated with upright PRA.The relation between lead-exposure and essential hypertension is discussed.     

Purification and characterization of canine urinary kallikrein

The renal kallikrein-kinin system may play a role in the regulation of sodium and water balance. Although the dog is a frequently used experimental animal in the study of the renal kallikrein-kinin system, dog urinary kallikrein (DUKK) has been poorly studied. We have purified DUKK by a series of chromatographic and electrophoretic procedures including anion-exchange chromatography, filtration through p-aminobenzamidine-Sepharose (to remove contaminating nonkallikrein esterases), gel filtration, isoelectric focusing, and molecular sieve HPLC. This DUKK preparation gave three protein bands on polyacrylamide gel electrophoresis, each having similar esterolytic and kininogenase activities and immunological identity. Preparative isoelectric focusing indicated the presence of multiple forms of kallikrein with pI's of 3.93, 4.05, 4.24, and 4.44, the species with a pI of 4.24 constituting the major component. Neuraminidase treatment converted all of the forms into the component with a pI of 4.44, suggesting the charge heterogeneity was due mainly to differences in sialic acid content. DUKK has a specific activity of 3 mg bradykinin eq/min/mg protein when partially purified dog kininogen is used as a substrate. It is a glycoprotein with a molecular weight of 40,500 (amino acid analysis best fit method) and an alkaline pH optimum (9.0-9.5). DUKK is resistant to soybean trypsin inhibitor and lima bean trypsin inhibitor but is inhibited by several serine protease inhibitors such as antipain, leupeptin, and p-aminobenzamidine. Phe-Phe-Arg-chloromethyl ketone is a very potent inhibitor of DUKK. Contrary to previous reports, DUKK is also inhibited by N-alpha-p-tosyl-L-lysine chloromethyl ketone and aprotinin, the inhibition by the latter being inversely related to the concentration of NaCl in the medium. The esterolytic and amidolytic activities of DUKK are inhibited by an increase in NaCl concentration of the medium. This inhibition may be related to a NaCl-induced conformational change in the enzyme moiety.     

Urinary kallikrein excretion in normotensive aging female rats

The effect of aging on the intrarenal kallikrein-kinin system activity was investigated in normotensive 3-, 10-, 20-, and 30-month-old female Wistar rats. Urinary kallikrein excretion was measured by three independent assays (immunoreactive concentration, kininogenase, and amidolytic activities) and was found to decrease progressively from 10 to 30 months. In the 30-month-old rats the urinary immunoreactive kallikrein excretion represented 40-44% of the level detected in 3-month-old rats. Active and total kallikrein exhibited the same magnitude of reduction. Furthermore, the active to inactive kallikrein ratio remained unchanged throughout the life period studied. The level of urinary kallikrein inhibitor was studied by measuring the recovery of purified rat urinary kallikrein added in the samples; no change was observed with aging. None of the factors known at present to influence kallikrein excretion could be evoked to explain this age-related decrease. It is therefore suggested that this decrease may reflect a progressive impairment of the intrarenal endocrine function or an alteration in the secretion of the enzyme.     

Immunological identification of rat urinary inactive kallikrein as a proform of tissue kallikrein

Antibody was raised against a synthetic undecapeptide (PS 11) which corresponds to the prosegment of the rat tissue kallikrein precursor. The potential to recognize rat urinary active or inactive kallikrein was assessed by an enzyme immunoassay method for PS 11, using beta-D-galactosidase as the labeling enzyme. The active kallikrein failed to compete with the enzyme-labeled PS 11 in binding to the antibody. The inactive kallikrein displaced the enzyme-labeled PS 11 in this enzyme immunoassay, and the displacement curve was in parallel with that of PS 11. These results indicate that rat urinary inactive kallikrein contains a prosequence recognized by the antibody to PS 11. This inactive kallikrein is probably a proform of tissue kallikrein.     

Isolation and characterization of human urinary kallikrein

Human urinary kallikrein was purified by gel filtration on Sephacryl S-200 and affinity chromatography on aprotinin-Sepharose, followed by ion exchange chromatography on DEAE-Sepharose. Thus an enzyme preparation with a specific activity (using AcPheArgOEt as substrate) of 1 100 U/mg protein was obtained. A specific bioligical activity of 2 300 KE/mg was measured in the dog blood pressure assay and of 0.742 HMW kininogen-U/mg, corresponding to the liberation of 787 micrograms bradykinin per mg enzyme per min from HMW-kininogen, in the rat uterus assay. In dodecyl sulfate electrophoresis two protein bands with apparent molecular weights of 41 000 and 34 000 were separated. The amino acid composition was determined and isoleucine was identified as the only aminoterminal amino acid. On isoelectric focusing six protein bands with isoelectric points of 3.75, 3.80, 3.90, 4.00, 4.05 and 4.25 were separated. The kinetic constants for the kallikrein-catalyzed hyrdolysis of AcPheArgOEt and D ValLeuArgNHNp were determined. The bimolecular velocity constant for the inhibition by diisopropyl fluorophosphate was determined as 9 +/- 2l x mol-1 x min-1. Immunological studies showed that a close relationship exists between the urinary enzyme and other human glandular kallikreins. Deoxycholate, lysolecithin and other amphiphiles activated human urinary kallikrein.     

Recent developments in urinary kallikrein research.

There have been numerous contributions to the knowledge of urinary kallikrein over the past few years. They throw light on the nature and the origin of urinary kallikrein, as well as improvements in the methods of measurement of its activity. The relationship of urinary kallikrein to salt and water excretion is critically reviewed; and its interaction with other renal endocrine hormonal systems highlighted.