Effect of copper deficiency and cis-diamminedichloroplatinum (II) treatment on the activities of renal microvillar enzymes in rats.

Recent studies have shown that some manifestations of cis-diamminedichloroplatinum (II) (cis-Pt) induced nephrotoxicity in animals may be exacerbated if the animals are nutritionally deprived of copper. The objective of the present study was to determine the effects of cis-Pt induced toxicity on enzyme activities in the kidney microvilli of rats with different copper statuses. Weanling male rats were fed copper-deficient (CuD) (less than 1 mg/kg Cu of diet) or copper-adequate (CuA) (5 mg/L of Cu in drinking water) regimens. After 24 days, rats were given i.v. injections of either cis-Pt (5 mg/kg BW) or saline in a 2 x 2 factorial design. At days 2 and 4 post-injection rats were killed and tubular microvilli isolated from the kidney cortex. Each preparation was assayed for the activities of 5 membrane-bound enzymes. Angiotensin-I converting enzyme (ACE) activity was 20 to 30% higher in the microvilli of CuD rats than in controls. Cis-Pt treatment enhanced ACE activity as well, and activity in treated rats was 60 to 110% higher than in controls. At day 2 there was a 20% greater increase in ACE activity in cis-Pt-treated CuD rats than in CuA rats. Aminopeptidase N activity was 35% lower in CuD rats than controls, but activity was not affected by cis-Pt. Gamma-glutamyltransferase activity was lowered by as much as 30% in cis-Pt-treated rats when compared to controls, but there was no effect of copper deficiency. Alkaline phosphatase and neutral endopeptidase 24.11 activities were significantly lower in microvilli of cis-Pt-treated rats than in those not treated.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic dissociation of multiple morphine effects among C57BL/6J, DBA/2J and C3H/HeJ inbred mouse strains.

The pattern of sensitivity of mice from three inbred strains were compared on measures of morphine-induced analgesia (hot plate), locomotor activity, hypothermia, Straub tail (muscular rigidity), antidiuresis and constipation. The DBA/2J strain emerged as the most sensitive strain for analgesia, retention of a water load (antidiuresis) and hypothermia. In addition, the DBA/2J mice had lower concentrations of morphine in the brain 30 min after injection and had the lowest Kd and the highest Bmax for naloxone as measured by in vitro receptor binding. In contrast, mice of the C57BL/6J strain were most sensitive when locomotor activity, Straub tail and constipation were measured. The C3H/HeJ mice were generally intermediate in their sensitivity to morphine. The observed strain differences indicate a rather high degree of genetic control for most of the effects studied, however, the low consistency of rank order among the three strains across these measures suggests that the genetically determined mechanisms are largely different between these measures of morphine sensitivity.

Selective breeding for levorphanol-induced antinociception on the hot-plate assay: commonalities in mechanism of action with morphine, pentazocine, ethylketocyclazocine, U-50488H and clonidine in mice.

Selective breeding (selection) was used to bidirectionally alter gene frequencies affecting levorphanol antinociception on the hot-plate assay in mice. After 12 generations of selective breeding, the high antinociceptive response line exhibited about 7 times steeper dose-response curve than did the low antinociceptive response line whereas only small differences were seen with saline alone. The authors sought to determine whether these large, genetically mediated differences in sensitivity bred into the high and low antinociceptive response lines (lineages) with levorphanol would also be evident with other analgesics. Should this occur with any particular drug, this would imply common mechanisms of action between that drug and levorphanol mediated by common gene action. This was found to be the case with morphine, but progressively less similarity to levorphanol was seen with other analgesics with the following rank order: morphine greater than pentazocine greater than ethylketocyclazocine greater than U-50488H greater than clonidine. Thus, the mechanisms of action for the latter compounds are different from levorphanol in varying degrees. The role of sedation produced by some of these drugs was also evaluated and was found to be independent of the antinociceptive effects. Thus, the latter was not confounded by the former in these genetic lines of mice.

Zinc deficiency and the kidney. II. Response of zinc-deficient rats to three diuretic drugs.

Carbonic anhydrase is a zinc metalloenzyme whose activity may be affected by zinc deficiency. This investigation was designed to evaluate the effect of zinc deficiency on the response to three diuretic drugs which vary in their capacity to inhibit carbonic anhydrase: acetazolamide, furosemide and hydrochlorothiazide. The response of the zinc-deficient rats was compared to that of pair-fed and ad libitum zinc-supplemented controls. The pattern of electrolyte excretion by zinc-deficient rats in response to the three diuretics was qualitatively similar to that of the pair-fed and zinc-supplemented rats. When corrected for differences in body weight between the three groups, the natriuretic response to the diuretics in zinc-deficient rats was greater than that of either the pair-fed or zinc-supplemented controls. Although administration of the diuretics increased potassium excretion in all groups, the response of the zinc-deficient rats was attenuated. These differences in the response of zinc-deficient rats to diuretics did not appear to be related to the capacity of these drugs to inhibit carbonic anhydrase.

Zinc deficiency and the kidney. I. Effect on renal carbonic anhydrase activity.

Tissue zinc concentration and the activity of the zinc metalloenzyme, carbonic anhydrase, were quantified in whole blood and kidneys of weanling male Sprague-Dawley rats with diet-induced zinc deficiency. Zinc-deficient rats were fed ad libitum a commercially prepared diet containing less than 1 ppm zinc. Zinc-supplemented rats were ad libitum or pair-fed a control diet containing 60 ppm zinc. All animals were fed their respective diets for 3-6 weeks. Body and kidney growth were severely compromised after 3 and 6 weeks of feeding the zinc-deficient diet. Plasma and kidney zinc concentrations were significantly decreased in zinc-deficient animals after 6 weeks. While whole blood carbonic anhydrase activity of zinc-deficient rats was significantly greater than zinc-supplemented animals after 6 weeks, no differences in renal carbonic anhydrase activity were found between zinc-deficient animals and pair-fed controls. Results reported in this study suggest that zinc deficiency imposed at weaning in rats may be a contributing factor to retarded kidney maturation and alterations in blood carbonic anhydrase activity.

Effect of acetazolamide on renal function of the newborn piglet.

The effects of renal development on the response of newborns to acetazolamide were determined in an animal model, 5- and 20-day-old piglets. Increasing doses of acetazolamide increased both sodium and potassium excretion in 5-day-old piglets. Sodium excretion increased from 1.89 muEq/min during control periods to 15.7 muEq/min during infusion of acetazolamide (75 mg/kg/h). Potassium excretion increased to 20 muEq/min during acetazolamide infusion and urine pH increased from 5.7 to over 8.0. Sodium excretion by 20-day-old piglets given acetazolamide was similar to that of 5-day-old piglets but potassium excretion was twice as great (40 muEq/min). Changes in urine pH of the two groups were identical. It is concluded that the natriuretic response of 5-day-old piglets to acetazolamide is similar to that of older animals. In newborn piglets, moderate increases in sodium excretion by acetazolamide were accompanied by a marked kaliuresis. These data may identify a role for carbonic anhydrase in potassium excretion by newborn similar to that of adults.

Effect of furosemide on renal function of the newborn piglet.

The effects of development of renal function on the response of newborns to furosemide was evaluated in an animal model, the newborn piglet. Three ages of piglets were used: 5-day-old, 20-day-old, and 50-day-old. Intravenous administration of furosemide (2 mg/kg) produced a prompt natriuresis in all animals. The natriuresis after furosemide was greatest in the older piglets (110 microEq/min for 50-day-old piglets were 210 microEq/min for 5-day-old piglets). However, the fractional sodium excretion at the peak of the response was near 20% in animals in each age group. Neither the time of peak response nor duration of natriuresis was affected by age. Potassium excretion increased after furosemide and remained elevated after both urine flow and sodium excretion had returned to control. The pattern of potassium excretion was identical for each of the three age groups. Thus, while renal maturation does not markedly affect the response to furosemide, both newborns and older piglets continue to excrete relatively large amounts of potassium after sodium excretion returns to control.

Effects of penicillin pretreatment on renal tubular para-aminohippurate transport in the immature rat.

The effect of pretreatment with penicillin on para-aminohippurate (PAH) transport by the kidney of the immature rat was evaluated in vivo. After 3 days of penicillin administration, renal clearances of inulin (CIN), PAH (CPAH), and the renal tubular transport maximum (Tm) for PAH were measured in rats as young as 17 days of age. The CPAH in 19- to 21-day-old rats pretreated with procaine penicillin was 54% greater than that of their littermate controls. Similarly, CPAH of rats that received sodium penicillin was 31% greater than control. CIN was not increased after penicillin pretreatment. Pretreatment of rats older than 24 days did not change CIN or CPAH. The Tm for PAH of 17-day-old rats pretreated with sodium penicillin was 51% greater than that of control rats. It was concluded that pretreatment with penicillin enhances the renal secretion of organic anions by the immature rat.

Pharmacological analysis of the action of diuretics in the newborn pig.

The effects of furosemide, ethacrynic acid, hydrochlorothiazide and amiloride on renal function of newborn piglets, 5 to 10 days old, were evaluated. Furosemide and ethacrynic acid were the most effective diuretics. Furosemide infusion at 0.5 mg/kg/hr inhibited reabsorption of 21% filtered sodium and ethacrynic acid, 1 mg/kg/hr, increased fractional sodium excretion to 29%. Hydrochlorothiazide infusion produced a milder natriuresis than furosemide or ethacrynic acid. Infusion of hydrochlorothiazide at 1.0 mg/kg/hr increased fractional sodium excretion from 0.3% during the control period to 7.2%. Furosemide, ethacrynic acid and hydrochlorothiazide each increased potassium excretion to near 20 microEq/min. amiloride (1.0 mg/kg/hr) increased fractional sodium excretion from 0.2% during control period to 2.8% during drug infusion but did not affect potassium excretion. When infused in combination with furosemide and hydrochlorothiazide, amiloride increased the natriuresis and decreased the kaliuresis of both diuretics. It is concluded that the unanesthetized piglet is a good model for renal function of immature mammals and responds to diuretics in a manner qualitatively similar to adults.

Effect of tolmetin on renal function and prostaglandin metabolism.

The effect of tolmetin on prostaglandin synthesis by minces of rat renal medulla and on prostaglandin cyclooxygenase of rabbit renal medulla was determined in vitro. The effect of tolmetin was compared to the effects of indomethacin and ibuprofen. Pretreatment of rats in vivo with tolmetin, indmethacin or ibuprofen reduced prostaglandin synthesis by minces of renal medulla. Incubation of medullary tissue in medium containing tolmetin or indomethacin also decreased prostaglandin production. Both drugs reduced O2 consumption by prostaglandin cyclooxygenase from rabbit renal medulla. In addition, the effect of tolmetin, indomethacin and ibuprofen on renal blood flow and the intrarenal distribution of renal blood flow was measured in anesthetized dogs. Tolmetin and ibuprofen resemble indomethacin in reducing renal blood flow and in shifting the distribution of renal cortical flow from the inner cortex toward the outer cortex. It is concluded that tolmetin is an effective inhibitor of prostaglandin synthesis and affects renal function in a fashion similar to other prostaglandin synthesis inhibitors.

Prostatic acid phosphatase activity in the postcoital vagina.

The present results are in general agreement with previous reports on the minimal level of AP activity that should be designated positive and on the period after intercourse in which elevated levels can be demonstrated. In this study 100% of the specimens above 25 KAu were taken within 48 hours of intercourse and 85.7% of these were within 24 hours. For values above 50 KAu, all were within 24 hours of intercourse. A low AP level does not rule out the possibility of recent coitus, particuarly if the woman was menstruating or had douched or used some suppository preparation. These findings also point to the possible interference of certain pathologies in correlating AP activity and time since coitus. As other authors have shown and this study has confirmed, some reactive substance seems to be present in the vagina at all times. For the use of AP assays in the forensic investigation of alleged rape cases, it is suggested that a thorough, accurate history be obtained with regard to douches and suppositories and that the presence of vaginal pathologies be noted. Further research on the techniques used in the forensic investigation of sexually related crimes is proceeding. The large proportion of negative samples within 24 hours of intercourse in this and other studies needs clarification. Other sampling techniques and the quantitative measurement of several different constituents of semen may offer accurate estimates of the time of last intercourse. Large studies with stringent control of the possible variables will further refine this important area of forensic science.