REDUCTION OF URINE VOLUME AMELIORATES ADRIAMYCIN-INDUCED NEPHROPATHY

1. Adriamycin, a commonly used antineoplastic antibiotic, induces glomerular lesions in rats, resulting in persistent proteinuria and glomerulosclerosis.2. The effect of urine volume on the progression of adriamycin-induced nephropathy was studied in 70 male Wistar rats (180-200 g) observed for 30 weeks and separated into 4 groups: healthy control group (HCG, N = 10) inoculated iv with 1 ml of saline, and nephrotic groups inoculated iv with a single dose of adriamycin of 3 mg/kg body weight. The nephrotic rats were separated into 3 groups (N = 20): nephrotic control group (NCG) receiving only adriamycin; dehydrated nephrotic group (DNG) water deprived for 36 h within each 48-h period, and furosemide nephrotic group (FNG) treated with 12 mg/dl furosemide, and 0.9 g/dl NaCl in the drinking water.3. The 30-week survival rates of the DNG (100%) and HCG (100%) were significantly higher than those of the NCG (85%) and FNG (55%).4. The proteinuria observed in the HCG (range, 7.38 +/- 0.7 to 13.6 +/- 1.27 mg/24 h) was significantly lower than that observed for all the nephrotic groups throughout the experiment. The DNG presented significantly less proteinuria (range, 42.71 +/- 6.83 to 140.10 +/- 19.22 mg/24 h) than the NCG (range, 35.32 +/- 7.64 to 250.00 +/- 25.91 mg/24 h) from week 10 on. There was no significant difference between the mean 24-h proteinuria of the NCG (range, 35.32 +/- 7.64 to 250.00 +/- 25.91 mg/24 h) and the FNG (range, 35.82 +/- 7.91 to 221.54 +/- 26.74).5. The mean frequency of damaged glomeruli was 0.3% +/- 0.3 for HCG, 42% +/- 6% for CNG, 40.8% +/- 8% for DNG, and 47% +/- 14% for FNG. The median value of the tubulointerstitial lesion, evaluated by a semiquantitative method, was 0 in HCG, 10 in CNG, 8.5 in DNG and 9.5 in FNG(P<0.05 for all groups compared to HCG).6. The data indicate that reduction of urine volume has a protective effect on adriamycin-induced nephropathy.

CHEMICAL SYMPATHECTOMY BLOCKS ANDROGEN BIOSYNTHESIS DURING PREPUBERTY

Twenty-one-day old male Wistar rats were injected subcutaneously with guanethidine (GUA) at doses of 5 and 10 mg kg(-1) day(-1) for 20 days. Animals were sacrificed by decapitation during the prepubertal (41 days of age) and early-pubertal (51 days of age) periods of sexual development. The testes were collected, frozen in liquid N-2 and stored at -70 degrees C until determination of testicular progesterone (P): androstenedione (A) and testosterone (T). Higher levels of P (2.18 +/- 0.24 ng/g. control = 1.24 +/- 0.16 ng/g) associated with decreased levels of androgens (A = 0.26 +/- 0.06 ng/g and T = 2.05 +/- 0.19 ng/g; control = 1.86 +/- 0.76 ng/g and 8.48 +/- 1.16 ng/g, respectively) were observed in 10 mg GUA-treated rats of prepubertal age, while only P levels (3.12 +/- 0.51 ng/g control = 1.73 +/- 0.27 ng/g) were increased in rats of early pubertal age. It is important to note that in 41-day old male rats both 5 and 10 mg were effective in decreasing testicular concentration of testosterone. These results suggest that the sympathetic innervation of the testis is involved in the modulation of androgen biosynthesis, acting through a selective step in the steroid biochemical pathway during the pubertal process and that under the conditions employed the blockage in androgen biosynthesis in the prepubertal stage of sexual maturation is dependent on the dose of GUA.

EFFECT OF CAFFEINE ON THE METABOLISM OF RATS EXERCISING BY SWIMMING

Several studies have demonstrated that caffeine improves endurance exercise performance but the mechanisms are not fully understood. Possibilities include increased free fatty acid (FFA) oxidation with consequent sparing of muscle glycogen as well as enhancement of neuromuscular function during exercise. The present study was designed to investigate the effects of caffeine on liver and muscle glycogen of 3-month old, male Wistar rats (250-300 g) exercising by swimming. Caffeine (5 mg/kg) dissolved in saline (CAF) or 0.9% sodium chloride (SAL) was administered by oral intubation (1 mu l/g) to fed rats 60 min before exercise. The rats (N = and-IO per group) swam bearing a load corresponding to 5% body weight for 30 or 60 min. FFA levels were significantly elevated to 0.475 +/- 0.10 mEq/l in CAF compared to 0.369 +/- 0.06 mEq/l in SAL rats at the beginning of exercise. During exercise, a significant difference in FFA levels between CAF and SAL rats was observed at 30 min (0.325 +/- 0.06 vs 0.274 +/- 0.05 mEq/l) but not at 60 min (0.424 +/- 0.13 vs 0.385 +/- 0.10 mEq/l). Blood glucose showed an increase due to caffeine only at the end of exercise (CAF = 142.1 +/- 27.4 and SAL = 120.2 +/- 12.9 mg/100 ml). No significant difference in liver or muscle glycogen was observed in CAF as compared to SAL rats, at rest or during exercise. Caffeine increased blood lactate only at the beginning of exercise (CAF = 2.13 +/- 0.2 and SAL = 1.78 +/- 0.2 mmol/l). These data indicate that caffeine (5 mg/kg) has no glycogen-sparing effect on rats exercising by swimming even though the FFA levels of CAF rats were significantly higher at the beginning of exercise.

ISOLATION OF BABESIA-BIGEMINA AND BABESIA-BOVIS MEROZOITES BY AMMONIUM-CHLORIDE LYSIS OF INFECTED ERYTHROCYTES

1. We describe the isolation of viable merozoites from erythrocytes infected with Babesia bovis or Babesia bigemina organisms by ammonium chloride lysis.2. Parasite morphology was examined by both light and transmission electron microscopy. Erythrocyte-free parasites maintain their viability and infectivity, retain their antigenicity and are suitable for use in the indirect fluorescent antibody assay.

Study of the embryotoxic effects of an extract of rosemary (Rosmarinus officinalis L)

Extracts of rosemary, Rosmarinus officinalis L., have been used in folk medicine as a diuretic, an emenagogue, an antispasmodic and its aqueous extract does not present toxicity to man, presenting, however, abortive effects. In order to evaluate if this plant induces abortion and/or interferes with the normal development of the concepts, doses of 26 mg of a 30% (w/v) R. officinalis aqueous extract (13 mg solids/ml) made with leaves, flowers and stem were administered daily by gavage during two different periods of Wistar rat pregnancy. One group of animals (N = 12) received the extract from days 1 to 6 of pregnancy (preimplantation period) and another group (N = 14) received the same extract from days 6 to 15 of pregnancy (organogenic period). Control groups (N = 12) received saline in the same volume and during the same periods as their respective experimental groups. The animals were sacrificed at term. The treatment of the darns during either the preimplantation or the organogenic period did not cause significant changes in the postimplantation loss or in the number of anomalies or malformations of the term fetuses, which also showed a similar degree of development when compared with the respective controls. The percent of preimplantation loss in the group treated before embryo implantation increased, although the difference was not significant compared to the control. This result suggests that rosemary extract may present an anti-implantation effect without interfering with the normal development of the concept after implantation.

ALPHA-ADRENERGIC PATHWAYS IN THE LATERAL HYPOTHALAMUS ARE IMPORTANT FOR THE DIPSOGENIC EFFECT OF CARBACHOL INJECTED INTO THE MEDIAL SEPTAL AREA

We studied the effect of the alpha(1)- and alpha(2)-adrenergic receptors of the lateral hypothalamus (LH) on the control of water intake induced by injection of carbachol into the medial septal area (MSA) of adult male Holtzman rats (250-300 g) implanted with chronic stainless steel cannulae into the LH and MSA. The volume of injection was always 1 mu l and was injected over a period of 30-60 s. For control, 0.15 M NaCl was used. Clonidine (20 nmol) but not phenylephrine (160 nmol) injected into the LH inhibited water intake induced by injection of carbachol (2 nmol) into the MSA, from 5.4 +/- 1.2 ml/h to 0.3 +/- 0.1 and 3.0 +/- 0.9 ml/h, respectively (N = 26). When we injected yohimbine (80 nmol) + clonidine (20 nmol) and prazosin (40 nmol) + clonidine (20 nmol) into theLH, water intake induced by injection of carbachol into the MSA was inhibited from 5.4 +/- 1.2 ml/h to 0.8 +/- 0.5 and 0.3 +/- 0.2 ml/h, respectively (N = 19). Water intake induced by carbachol (2 nmol) injected into the MSA was decreased by previous injection of yohimbine (80 nmol) + phenylephrine (160 nmol) and prazosin (40 nmol) + phenylephrine (l60 nmol) from 5.4 +/- 1.2 ml/h to 1.0 +/- 0.7 and 1.8 +/- 0.8 ml/h, respectively (N = 16). The cannula reached both the medial septal area in its medial portion and the lateral hypothalamus. It has been suggested that the different pathways for induction of drinking converge on a final common pathway. Thus, adrenergic stimulation of alpha(2),-adrenoceptors ofLH can influence this final common pathway.

PARTICIPATION OF MACROPHAGES IN CHLORAMPHENICOL-POTENTIATED CARRAGEENAN-INDUCED PERITONITIS IN RATS

1. We investigated the possible potentiating effect of chloramphenicol succinate (30 mg/kg, every 12 h for 4 days, ip) on the response of polymorphonuclear neutrophils to carrageenin (150 mug, ip) or dextran (100 mug, ip) in the peritoneal cavity of male Wistar rats (180-230 g; N = 12 in each group).2. Chloramphenicol potentiated the cell migration induced by carrageenin (35%) but not that induced by dextran. Previous macrophage depletion in the peritoneal cavity by washing with sterile saline abolished the cell response, whereas a previous thioglycollate-induced increase in macrophage numbers enhanced the potentiating effect (60%).3. These results suggest that the potentiating effect on polymorphonuclear neutrophil migration induced by chloramphenicol may be related to chemotactic factors released by macrophages.