[Neurohumoral, autacoid and transductional mechanisms in the cardiovascular effects of vanadate: histochemical correlations]. / Meccanismi neuroumorali, autacoidali e trasduzionali negli effetti cardiovasali di vanadato: correlati istochimici.

Rabbits given 1 ppm of vanadate in drinking water for twelve months showed (a) increased plasma levels of catecholamines (b) reduction of the arterial concentration of nitric oxide (c) lower activity of urine kallikrein and higher activities of urine kininases I and II and enkephalinase (d) reduced cardiac inotropism and augmented total peripheral resistance, with unchanged blood pressure levels (e) accumulation of the metal in the aorta and cardiac ventricles. Monoaminooxidase and glucose-6-phosphate dehydrogenase activities were increased by vanadate in both kidney and liver and that of NADH-diaphorase in the kidney, in which NADPH-diaphorase activity was reduced. Some of the above results were also obtained in rats given 10 and 40 ppm of vanadate in drinking water for six-seven months; these animals showed arterial hypertension and reduced activity of Na, K-ATPase in the kidney. Vanadium appears to act on the cardiovascular function through selective neurohumoral, autacoidal and transductional mechanisms only in part depending on the species.

Significance of renal kininases in patients with Cushing's syndrome.

To further clarify the significance of renal kininases in patients with Cushing's syndrome, daily urinary excretions of total kininase, kininase I, Ii and neutral endopeptidase 24.11 (NEP) were examined and evaluated for the relations between plasma cortisol level and these kininases. Urinary total kininase kininase I, II and NEP were significantly higher in patients with Cushing's syndrome than in normotensives. There was a significant positive correlation between plasma cortisol level and total kininase or NEP, and the same tendency was observed between plasma cortisol level and kininase I. After adrenalectomy, urinary kininases decreased to normal levels. These findings suggested that: 1) kininase I, II and NEP are accelerated in Cushing's syndrome; 2) glucocorticoids may regulate renal kininases; and 3) accelerated renal kininases may play some role in disorders of the renal water-sodium metabolism and in high blood pressure in Cushing's syndrome.

Significance of renal kininases in patients with primary aldosteronism.

To elucidate the significance of renal kininases in primary aldosteronism (PA), urinary total kininase, kininase I, II and neutral endopeptidase 24.11 (NEP) were examined and evaluated for the regulation mechanisms of these kininases. Total kininase, kininase I and NEP were significantly higher in PA than in normotensives (NT), whereas no difference was found for kininase II. Moreover, 42% of total kininase consisted of unknown kininase(s), different from kininase I, II or NEP. There were significantly positive correlations between plasma aldosterone concentration and total kininase, kininase I and unknown kininase(s) in PA. After the adrenalectomy, urinary kininases decreased into normal ranges, and unknown kininase(s) were negligible. These findings suggested that: 1) kininase I and NEP are accelerated in PA; 2) unknown kininase(s) differing from kininase I, II or NEP may exist in PA; 3) mineralocorticoids may regulate renal kininases; and 4) accelerated renal kininases may play some role in disorders of the renal water-sodium metabolism and in high blood pressure in PA.

Renal toxicity and arterial hypertension in rats chronically exposed to vanadate.

The effects of 1, 10, or 40 micrograms/ml of vanadium, given for six or seven months as sodium metavanadate in drinking water on cardiovascular and biochemical variables and the electrolyte metabolism of male Sprague-Dawley rats were investigated. At the end of the exposure period, all animals exposed to vanadate had increased systolic and diastolic blood pressure. This effect was not dose dependent and heart rate and cardiac inotropism were not affected. The role of defective renal function and electrolyte metabolism in such effects was supported, in the rats exposed to 10 and 40 ppm of vanadium, by the following changes: (a) decreased Na, + K(+)-ATPase activity in the distal tubules of nephrons; (b) increased urinary excretion of potassium; (c) increase in plasma renin activity and urinary kallikrein, kininase I, and kininase II activities; (d) increased plasma aldosterone (only in the rats treated with 10 ppm of vanadium). The alterations in the rats exposed to 1 ppm of vanadium were: (a) reduced urinary calcium excretion; (b) reduced urinary kallikrein activity; (c) reduced plasma aldosterone. These results suggest that blood hypertension in rats exposed to vanadate depends on specific mechanisms of renal toxicity related to the levels of exposure.

Components of plasma and tissue kallikrein-kinin system in the urine of patients with latent, nephrotic and hypertonic forms of glomerulonephritis.

Activities of main components of KKS were estimated in the urine of patients with latent, nephrotic and hypertonic forms of chronic glomerulonephritis (ChGN) and compared to those parameters in urine of healthy persons. The data obtained allow to make a conclusion concerning the pathogenetic and the compensatory role of plasma KKS in the nephrotic form of ChGN.

Renal kininases in primary aldosteronism.

In order to further clarify the role of renal kallikrein-kinin (K-K) system in primary aldosteronism (PA), daily urinary excretions of renal K-K system components including kallikrein (KAL), kinin (KIN), total kininase (K-ase), K-ase I, K-ase II and neutral endopeptidase (NEP) were measured in PA and normotensives (NT). In this study, a new method for the simultaneous determination of human urinary K-ase I, II and NEP was established and employed. The daily excretions of KAL was significantly higher in PA than that in NT, while no difference was found in KIN between PA and NT. On the other hand, total K-ase in PA (897 +/- 258 micrograms/min/day) was significantly higher than that in NT (209 +/- 6). NEP was also significantly higher in PA (262 +/- 22 micrograms/min/day) than that in NT (127 +/- 6), whereas there were no differences in K-ase I and K-ase II between PA and NT. The relative contributions of K-ase I, II and NEP to total K-ase in NT were 14, 27 and 59%, while those in PA were 12, 17 and 36%, respectively. As a result, these three K-ase contributed only 64% to the total K-ase in PA. These findings suggested that 1) NEP may play a major role in the catabolism of renal KIN in human, 2) NEP is accelerated in PA, 3) unknown K-ase, different from K-ase I, II or NEP, may exist in PA, and 4) accelerated renal K-ase activity may play some role on the disorder of renal water-sodium metabolism and high blood pressure in PA.

A sensitive method for differential determination of kininase I, II and neutral endopeptidase (NEP) in human urine.

In order to clarify the significance of NEP in human renal kallikrein-kinin system, an assay system was developed for the simultaneous determination of kininase I, II and NEP activities in human. Each kininase activity was determined by measuring the hydrolysis of bradykinin in the presence of specific inhibitors of kininase I (2-mercaptomethyl-3-guanidinoethylthiopropanoic acid), kininase II (captopril) and NEP (phosphoramidon) in 8 normal subjects. The effects of the different assay buffers on kininase activities were also investigated by using a phosphate buffer. Total kininase, kininase I, II and NEP activities were 499 +/- 65 ng/min/ml (mean +/- S.E.), 55 +/- 8, 141 +/- 21 and 299 +/- 42, respectively in our method using a tris buffer, while a phosphate buffer brought about activities of 358 +/- 43, 45 +/- 5, 156 +/- 21 and 135 +/- 25 ng/min/ml. The relative contributions of kininase I, II and NEP to total kininase activity were 11, 29 and 59% in our assay system, while they were 13, 44 and 35% when a phosphate buffer was used. From these results it was suggested that 1) phosphate may inhibit urinary NEP activity, so that a tris buffer should be used as the incubation buffer, 2) NEP is the major component of human urinary kininases, and 3) NEP may play an important role in the renal kallikrein-kinin system.

Localization of neutral endopeptidase in the kidney determined by the stop-flow method.

Recently, the existence of neutral endopeptidase (NEP) as a new kininase in the kidney has been reported. In this study, the localization of NEP in the nephron was investigated and compared with other components of the renal kallikrein-kinin (K-K) system by using a stop-flow method in dog kidneys. The stop-flow method was performed according to the procedures previously reported by Scicli et al and Malvin et al. Five mongrel dogs (weighing 15-20 kg) were used in this study. Kininase I, II and NEP were measured by the modified procedure of Ura et al. Kallikrein and kinin were found in the distal tubules, and kininase I and II were observed in both the distal and proximal tubules. NEP was localized mainly in the proximal tubules. A small peak was also recognized in the distal tubules. From these results, it was suggested that, not only kininase I and II but also NEP existing in the proximal tubules may destroy kinin filtered from the glomeruli, and these kininases existing in the distal tubules may play an important role in connection with kinin producing enzymes on the regulation of activity in the renal kallikrein-kinin system.

Kallikrein and kininase activities excretion in newborns affected by jaundice.

In a homogeneous group of 30 newborns, aging between 10 hours--10 days, and affected by jaundice, urinary kallikrein and kininase activities were determined. The variable considered were: sex, time of life, weight and gestational age. Urinary samples were taken at the beginning and at the end of phototherapy.

Kallikrein and kininase excretion in football players after psychophysical stress.

In eleven football players and in four football-reserve players urinary kallikrein and kininase activities were determined before and after an official match. The results showed a significant reduction of kallikrein after the match in football players when the football-reserve players were used for comparison (p less than 0.01). Kininase activity appears increased in football players after the match, but not significantly. The Kininase/Kallikrein ratio after the match resulted significantly increased in football players (p less than 0.05) and very significantly compared to the football-reserve players (p less than 0.01).

Urinary excretions of kininase I and kininase II activities in essential hypertension. A sensitive and simple method for its kinin-destroying capacity.

To further clarify the role of the renal kallikrein-kinin system in essential hypertension, a sensitive and simple method for the determination of both human urinary kininase I and kininase II was established, and the system components were determined in patients. In the measurement of kininase activity, desalted urine samples were incubated with synthetic bradykinin, and the reaction was terminated with kininase inhibitors, ethylene diamine tetraacetic acid and phenanthroline. Thus, kininase activity was determined as the kinin-destroying capacity. Moreover, the specific inhibitor for kininase II, SQ14225, was applied for the separation of kininase I and kininase II activities. Daily urinary excretions of total kininase and kininase I activities were significantly higher in essential hypertensive patients than those in normotensive subjects, whereas no difference was observed in kininase II activity. As reported previously, daily excretions of urinary kallikrein and kinin simultaneously determined in these patients were significantly lower than excretions in normotensive subjects. From these results, it was suggested that not only decreased renal kallikrein, but also increased kininase activity, may play an important role in the suppression of the renal kallikrein-kinin system through the reduction of active kinin level in essential hypertension.

Study on the renal kallikrein-kinin system in normal and low renin subgroups of essential hypertension.

In order to investigate the role of the renal kallikrein-kinin (K-K) system in normal (NRH) and low renin (LRH) subgroups of essential hypertension (EHT), daily excretions of urinary kallikrein (KAL) quantity and activity, kinin (KIN), total and pre-KAL, and kininase I and II were measured in 21 normotensives (NT), 29 patients with NRH and 16 patients with LRH. The daily excretions of both KAL quantity and activity, total and pre-KAL, and KIN were significantly lower in NRH and LRH than in NT. That of kininase I was significantly higher in NRH and LRH than in NT, but that of kininase II was not. In comparing NRH and LRH, the urinary excretions of KAL activity and KIN were lower in LRH than in NRH, and that of kininase I was higher in LRH than in NRH. The KAL/total KAL ratio did not show any significant difference among NT, NRH and LRH. These findings suggest that the suppression of the renal K-K system in EHT seems to be due to both the decrease of KAL through the pre-KAL synthesis in the kidney and an increase of kininase I activity, but not to the inhibition of conversion from pre-KAL to active KAL and the more obvious suppression of this system in LRH than in NRH may be partly explained by KAL inhibitors and/or increased kininase I activity.

A case of 17 alpha-hydroxylase deficiency with special reference to the renal kallikrein-kinin system.

In a 26-year-old male with 17 alpha-hydroxylase deficiency, endocrinological examinations were performed not only after, but also before the onset of clinical signs and symptoms. In addition, the pathophysiological role of the renal kallikrein-kinin system was investigated in this patient. In spite of the fact that this disease is congenital, in the mechanism of its onset, this patient had a period of endocrinological normality before onset; that is, 9 months before onset, both ACTH and cortisol were within the normal range, although the former would be significantly higher and the latter significantly lower than normal values after the onset. In this case, both urinary kallikrein and kininase excretions abnormally increased and then returned to normal after dexamethasone treatment.

Components of the kallikrein-kinin system in urine.

The excretion of kallikrein in urine varies, but the pathophysiologic implications are not clear. To help clarify the role of the urinary kallikrein-kinin system, we have begun to define components of the system as they occur in urine. To minimize artifacts which may arise through extensive purification procedures, we studied urinary protein concentrates prepared by ultrafiltration. The concentrates were separated by chromatography on Sephacryl. Urine contains abundant kininase activity, but in strongly inhibited forms. Kininase II is separable into at least two forms. Another major kininase can hydrolyze benzoyl-Pro-Phe-Arg and is inhibited by arginine but not by BPP9a or SQ 14,225. Its molecular weight is approximately 63,000. A third kininase, not inhibited by BPP9a, is excluded from Sephacryl. Human urine appears to contain only one kallikrein-like enzyme (MW 45,000). In addition, urine contains a protein (MW approximately 80,000) which reacts with trypsin to release bradykinin and which inhibits the hydrolysis of Pro-Phe-Arg-[3H]anilide by urinary kallikrein. Thus, in addition to kallikrein and kinins, urine contains kininogen and at least three kininase enzymes. Urinary ultrafiltrate contains an inhibitory substance (approximately MW 400).