Urinary kallikrein in Dahl-Iwai salt-sensitive and -resistant rats.

This study was designed to evaluate the differences between the renal kallikrein in newly established Dahl-Iwai rats under salt loading and that of Sprague-Dawley rats (SD). Urinary kallikrein quantity and activity was markedly lower in Dahl-Iwai rats than in SD even during the control period. Moreover, kallikrein quantity and activity in Dahl-Iwai salt-sensitive rats (SS) were clearly diminished in comparison with salt-resistant rats (SR). The kallikrein activity/ quantity ratio was also lower in SS and SR than in SD during the control period. After salt loading, systolic blood pressure increased only in SS. Kallikrein activity in SS and SR, and kallikrein quantity in SS were increased, whereas those in SD did not change. Although the kallikrein activity/quantity ratio in SR reached the same level in SD after salt loading, that in SS was lower throughout the experiment. These results suggest that Dahl-Iwai rats are less able hereditarily to produce renal kallikrein and that there may exist structurally abnormal kallikrein that may have a lower activity. Different kinetics of renal kallikrein between SS and SR by salt loading might be explained by kallikrein inhibitors or abnormal kallikrein or nonkallikrein kininogenase. These different kinetics of renal kallikrein may play some role on blood pressure elevation in SS.

Dietary L-arginine supplementation normalizes regional blood flow in Dahl-Iwai salt-sensitive rats.

We performed the present study to determine 1) whether different organs undergo similar increase in vascular resistance in Dahl-Iwai salt-sensitive (S) rats, and 2) the effects of chronic oral L-arginine supplementation on the regional hemodynamics in S rats. Male 6 week old S rats and Dahl-Iwai salt-resistant (R) rats were maintained on an 8% NaCl chow for 4 weeks. One group (S or R rats) was maintained on tap water and the other group (S/Arg) of S rats received tap water containing L-arginine at a concentration of 1.5%. Organ blood flow and cardiac output were measured with microspheres in the conscious condition. Concerning regional hemodynamics, the flow rate of the kidney was lower in S rats than in R rats, but there were no differences between S and R rats in the flow rates of the brain, heart, lung, liver, spleen, intestine, skeletal muscle and skin. The flow rate of the kidney in S/Arg rats was maintained at a higher level as compared to that of S rats. Urinary excretion of protein and albumin in S/Arg rats was significantly suppressed when compared to S rats. Thus, the supplementation of L-arginine normalized the abnormality of renal hemodynamics accompanying salt-induced hypertension. It is suggested that the disturbance in the production of nitric oxide may induce salt-sensitive hypertension and the abnormality of renal hemodynamics in the S rats.

Vitamin E ameliorates the renal injury of Dahl salt-sensitive rats.

Recently, hyperlipidemia as well as hypertension has been observed in Dahl salt-sensitive (S) rats. In this study, to investigate whether the lipid abnormality is involved in the renal injury of Dahl S rats, we examined the effect of vitamin E on glomerular sclerosis, as vitamin E is an inhibitor of lipid oxidation. Dahl S rats were given a high salt diet (8% NaCl) containing either normal vitamin E (2 mg/100 g) or high vitamin E (50 mg/100 g) for 4 weeks. Dahl salt-resistant (R) rats were given a high salt and normal vitamin E diet. The blood pressure in the Dahl rats increased and was not suppressed by the vitamin E supplement. Serum cholesterol and triglycerides in Dahl S rats were higher than in Dahl R rats at both 0 and 4 weeks. Vitamin E lowered the serum cholesterol level in Dahl S rats at 4 weeks (126 +/- 5 v 150 +/- 12 mg/dL, P < .01). Urinary protein excretion and serum creatinine increased in Dahl S rats, and vitamin E inhibited the increases significantly (urinary protein, 70.7 +/- 0.9 v 178.0 +/- 8.8 mg/day, P < .01; serum creatinine, 0.45 +/- 0.02 v 0.63 +/- 0.05 mg/dL, P < .01). Serum lipid peroxide (LPO) was higher in Dahl S rats than in Dahl R rats, and vitamin E lowered LPO in Dahl S rats (2.10 +/- 0.03 v 2.70 +/- 0.04 nmol/mL, P < .01). In the histologic study, sclerosing score (SS) of glomeruli, which represents the degree of glomerulosclerosis semiquantitatively, was higher in Dahl S rats than in Dahl R rats. Vitamin E lowered SS (114 +/- 3 v 157 +/- 6, P < .01) and ameliorated arterial injuries such as medial thickness with partial necrosis and severe fibrinoid proliferation with inflammatory cell infiltration. In all rats, SS was strongly correlated with urinary protein (r = 0.93, P < .01), serum cholesterol (r = 0.86, P < .01), and serum LPO (r = 0.89, P < .01). These results suggest that the renal injury in Dahl S rats is caused not only by hypertension but also by hyperlipidemia. Therefore, vitamin E might ameliorate the renal damage by inhibiting the oxidation of lipids.

Endogenous creatinine clearance in the rat: strain variation.

The clearance of endogenous creatinine was examined in five strains of rats (Wistar, Wistar Kyoto, Spontaneously Hypertensive Rats, Biobreeding/Worcester diabetic prone and diabetic resistant rats). Creatinine clearance was compared with inulin clearance as the standard. Conditions for clearance measurements were also varied (anesthesia with constant infusion, overnight collection of urine, fed vs. unfed state, single-injection technique). The clearance of creatinine adequately reflects the glomerular filtration rate in three strains (Wistar, Wistar-Kyoto and the Spontaneously Hypertensive Rat). In the two strains of the Biobreeding/Worcester rat creatinine clearance is consistently lower than the inulin clearance. When creatinine clearance is measured from an overnight collection of urine with food withheld it is always lower than when food is present. This clearance should always be validated by comparison with inulin clearance measured simultaneously or under comparable conditions. The ease with which endogenous creatinine clearance can be measured makes it a reasonable method when large numbers of repeated determinations of glomerular filtration rate are required.

Avaliaçäo da citratúria normal em ratos / Evaluation of normal citraturia in rats

Em uma populaçäo de ratos Wistar, foi avaliado o padräo normal de excreçäo do citrato urinário, sendo observado que: 1) a citratúria normal variou amplamente, de animal para animal; 2) os animais mais idosos (AM > 350) excretaram menos citrato por mg de creatinina (4,7 vs. 7,8 umol de cit/mg de creat) ou citrato/100G PC (12,9 vs. 22,0umol cit/100G) rato do que os ratos mais jovens (AJM); 3) a concentraçäo urinária do citrato, creatinina, cálcio, fósforo, sódio e potássio tiveram correlaçäo linear negativa (p < 0,05) com o volume urinário; 4) a excreçäo do citrato (umol/24h) apresentou correlaçäo positiva (p < 0,05) com a excreçäo de 24 h da creatinina, cálcio, fósforo, sódio e potássio; 5) a concentraçäo e excreçäo urinária do citrato, em ratos Wistar, foi significatemente maior no período diurno (8 às 20hs) vs. período noturno (20 às 8h); 6) a excreçäo do citrato em urina de 24h dos ratos machos adultos jovens (AJM: 7,8 umol cit/mg creat ou 22,0umol cit/100g de rato) foi significantemente maior do que a das fêmeas adultas jovens (AJF: 6,0umol cit/mg creat ou 13,3umol/100g de rato

Evaluation of methods for determining N-acetyl-beta-D-glucosaminidase in urine of rats without purification of urine samples.

N-Acetyl-beta-D-glucosaminidase (NAG) activities in urine of rats were measured with methods recommended as procedures without the pretreatment of urine sample. Four different derivatives [4-nitrophenyl; 3-cresolsulfonephthaleinyl; 3,3'-dichlorophenylsulfonephthaleinyl; 2-methoxy-4-(2-nitrovinyl)phenyl] of N-acetyl-beta-D-glucosaminide were compared for determination. The conventional test using the 4-nitrophenyl derivative showed the highest activities and was very well correlated with the other tests. The test using the 3,3'-dichlorophenylsulfonephthaleinyl substrate is most convenient and practical to determine NAG in small animals because it is, in contrast to the other three discontinuous (endpoint) tests, a continuous (kinetic) assay which can be easily adapted to clinical chemistry analyzers.

High performance concentration and gel filtration of rat urinary protein allergens.

Allergies to laboratory animals, notably rats, have become an increasingly recognized occupational problem. Identification and isolation of the individual proteins causing allergic reactions, could form the basis for early recognition of sensitivity, diagnosis, control of degree of pollution of the environment and desensibilization treatments. Frequently, allergens originate from dried rat urine. Because earlier published methods were found unsatisfactory we have developed a new strategy for isolation of rat urinary proteins including a high performance technique for their mild concentration on hydroxyapatite. The concentrated allergens have been fractionated according to molecular size by high performance gel filtration and according to carbohydrate content by wheat germ lectin-Sepharose 6 MB affinity chromatography. The obtained fractions have been examined by denaturing and non-denaturing polyacrylamide gradient gel electrophoresis followed by sensitive staining procedures, and tested with respect to allergenicity by skin tests on allergic patients.

On the pathogenetic mechanism of hypercalciuria in genetically hypertensive rats of the Milan strain.

The aim of this study was to investigate the pathogenesis of hypercalciuria in the Milan strain of genetically hypertensive rats. Dietary calcium intake and urinary and fecal calcium output were measured simultaneously with indices of sodium and phosphate homeostasis in male rats of the Milan hypertensive and normotensive strains. In addition, urinary calcium and creatinine excretion rates, calcium, phosphate and creatinine serum concentrations, and bone calcium content were also measured in these rats after an overnight fast. Under fed steady-state conditions dietary calcium, sodium, and phosphate intakes, were similar in the two groups of rats, but hypertensive rats had twofold higher urinary calcium excretion and normal urinary excretion of sodium and phosphate. Fecal calcium output was slightly but significantly higher in the adult hypertensive rats while fecal sodium and phosphate excretion was normal. Because of increased urinary and fecal calcium loss, net calcium balance was significantly less positive in hypertensive than in control rats. Under fasting conditions hypertensive rats were confirmed to have hypercalciuria despite normal serum calcium concentrations and normal creatinine clearance. In accordance with balance data and fasting hypercalciuria, bone calcium content was found to be significantly reduced in hypertensive rats. These findings confirm that hypercalciuria in the Milan hypertensive rats is explained by an altered renal calcium handling; it is also associated with a slightly increased fecal calcium output and, therefore, with a less positive calcium balance and reduced bone calcium content.

Han/Wistar rats are exceptionally resistant to TCDD. I.

Adult male Han/Wistar rats were administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) intraperitoneally at doses ranging from 125 to 1400 micrograms/kg and monitored for 39 to 48 days. Two rats succumbed in the course of the experiment: one in the group receiving 625 and one dosed 1000 micrograms/kg. Body weights of the animals decreased by 20 to 30% during the first 10 to 14 days and became stable thereafter. Feed consumption decreased to 1/3-1/2 of control levels by Day 4 (calculated per metabolic body mass) and returned gradually to starting values by about 4 weeks after dosing. Water intake displayed a triphasic pattern: at first it was slightly increased (Days 1 to 3), then reduced (on Days 4 to 12) and finally increased again throughout the remainder of the test period. The absolute and/or relative weights of thymus, testicles, ventral prostate and interscapular brown fat were significantly decreased at termination. These results indicate that the LD50-value for TCDD in the male, adult Han/Wistar rat is substantially above 1400 micrograms/kg, and that suppression of appetite is the principal phenomenon responsible for TCDD-induced body weight reduction.

Effect of diets containing dry beans (Phaseolus vulgaris, L.) on the rat excretion of endogenous nitrogen.

Wistar rats of 60.5 +/- 5.0 g fasted for 24 h were injected intraperitoneally with 10 microCi of [14C]glycine. One to two hours after injection the rats were fed a diet containing 10.53 +/- 0.75% protein provided by dry beans or casein, or a protein-free diet and submitted to a 4-d nitrogen balance. Radioactivity in the feces of rats fed casein, cooked beans and raw beans was roughly 2, 5 and 10 times greater, respectively, than in the feces of those fed the protein-free diet. Apparent protein digestibility showed a strong negative linear correlation (r = -0.9805, P less than or equal to 0.01) with radioactivity in the feces. Positive correlation (P less than or equal to 0.01) was demonstrated between radioactivity and either total carbon or total nitrogen in the feces of rats injected with [14C]glycine. Mean value for the radioactivity in the urine of rats fed the different diets did not differ significantly (P less than or equal to 0.05). Endogenous nitrogen excretion of rats on bean diets was estimated by the ratio of total endogenous N to marker N, based on the protein-free diet. The results indicated that rats fed bean-containing diets excreted significantly more endogenous nitrogen than those fed the casein diet, even though the casein diet had stimulated twice as much endogenous excretion than the protein-free diet. As a consequence, apparent digestibility and biological value of bean protein are generally underestimated, although the "real" biological value was not affected by the endogenous nitrogen excretion of the rat.

[Decrease in urinary excretion of active kallikrein in conscious young and adult spontaneously hypertensive rats]. / Réduction de l'excrétion urinaire de kallicréine active de rats spontanément hypertendus conscients jeunes et adultes.

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)

Pathogenesis of hypercalciuria in spontaneously hypertensive rats.

The etiology of hypercalciuria remains unknown in spontaneously hypertensive rats (SHR). In order to differentiate absorptive versus renal hypercalciuria, serial measurements of urinary calcium (UCaV) excretion were made weekly under fasting (3-hour urine collection) and after oral administration of CaCl2 (50 mg/100 g; 4-hour urine collection) from age 8 to 14 weeks in SHR (n = 14) and normotensive Wistar Kyoto rats (WKY; n = 14). Fasting UCaV was significantly greater in WKY than in SHR throughout the periods of observation. In contrast, after oral Ca loading UCaV was greater in SHR after 13 weeks of age (13 weeks: SHR UCaV = 954 micrograms/mg creatinine, WKY UCaV = 541 p less than 0.01; 14 weeks: SHR UCaV = 988 micrograms/mg creatinine, WKY UCaV = 534, p less than 0.01). Fasting urinary cyclic adenosine monophosphate (AMP) excretion was not different between WKY and SHR. However, cyclic AMP excretion of SHR, but not WKY, was decreased after calcium loading when compared to the fasting values. The cyclic AMP was also significantly lower in SHR than in WKY rats after calcium loading. Calcium handling by the kidney was not different between SHR and WKY with or without parathyroidectomy. Calcium disposition kinetic studies were performed on these animals at age 15 and 16 weeks. No significant difference of intravenous 45Ca was observed between WKY (n = 6) and SHR (n = 6) in total plasma clearance, nonrenal clearance, biologic half-life, and elimination rate constant from the central compartment. However, the WKY had a significantly greater renal clearance of 45Ca than the SHR (0.48 +/- 0.04 vs. 0.24 +/- 0.02 ml/n, p less than 0.001). Since tissue disposition of intravenous 45Ca was not different between WKY and SHR, the increased renal excretion of calcium after oral administration in SHR, therefore, reflects increased intestinal absorption of calcium. Correction of established hypertension did not abolish the hypercalciuria. We believe that increased gastrointestinal absorption of calcium is responsible for the hypercalciuria in SHR.

Resynchronization patterns for urinary rhythms in rats after light-dark shifts.

Diurnal urinary rhythms during a fixed 12:12 light-dark cycle were studied in male and female rats. After a control period of 9 days the light-dark cycle was shifted either +6 or -6 h by delaying or advancing the light period, respectively. Subsequently the resynchronization process was studied for 19-21 days. In both male and female rats an asymmetry effect was present: resynchronization was more rapid after a -6-h shift than after a +6-h shift. However, female rats exhibited a rate of resynchronization slower than male rats. During the process of resynchronization a state of transient internal dissociation was found for all urinary constituents. These results probably point to different control systems rather than to different circadian pacemakers. Further analysis of the role of sex steroid hormones is required in view of the sex variations reported.

Increased o- and p-cresol/hippuric acid ratios in the urine of four strains of rat exposed to toluene at thousands-ppm levels.

Rats (Fisher, Wistar, Donryu and Sprague-Dawley strains) were exposed to 5 approximately 3500 ppm toluene for 8 h, and urine samples were analyzed for hippuric acid and cresols. While hippuric acid increased in proportion to the exposure concentration, a sharp increase in o-cresol excretion was observed at high toluene concentrations so that the o-cresol/hippuric acid ratio was elevated after 500 approximately 3500 ppm exposures. Changes in the p-cresol: hippuric acid ratio were less marked. There were strain differences in toluene metabolism. Fisher rats were highest and Sprague-Dawley rats lowest in o-cresol excretion and in the o-cresol: hippuric acid ratio, whereas Wistar rats excreted p-cresol most abundantly.

Comparative study of alanine-amino-peptidase and gamma-glutamyl-transferase activity in normal Wistar rat urine.

24 h urinary alanine-amino-peptidase (AAP) and gamma-glutamyl transferase (GGT) activities were studied from the 3rd-7th month of life in male Wistar rats. A close relationship was found between AAP and GGT activity, except at the beginning and at the end of this period. At the end there appear 2 subgroups, the larger (70%) showing a strong correlation between AAP and GGT activity and the other (30%), demonstrating no correlation at all. A good correlation between AAP and GGT activities, creatinine, 24 h urine volume and 24 h creatinine output was found.