Atrial natriuretic factor (ANF) is a peptide originally found to be present in extracts of mammalian atria that possess marked natriuretic and diuretic qualities. A number of mechanisms have been suggested to explain these properties. Recently, it has been suggested that ANF may enhance glomerular filtration. In this report, we describe a series of experiments designed to investigate if atriopeptin II, a 23-amino acid synthetic analogue of ANF, increases glomerular filtration rate (GFR) and, if so, the mechanism for this increase. We used the isolated perfused glomerulus technique (n = 6), which allows a single isolated glomerular unit to be perfused and the determinants of single-nephron GFR (SNGFR) to be measured. Two periods were performed in each experiment, the control followed by the experimental. The only difference between the two periods was the addition of atriopeptin II to the experimental perfusate at a final concentration of 5 X 10(-7) M. There was indeed a significant increase in the SNGFR (78 +/- 27 to 108 +/- 29 nl/min, P less than 0.01). This increase was associated with a significant increase in the glomerular capillary hydrostatic pressure (PGC) from 31 +/- 3 to 35 +/- 3 mmHg (P less than 0.05). The filtration fraction also increased in each experiment (from 0.16 +/- 0.3 to 0.25 +/- 0.03, P less than 0.005). Neither the afferent flow nor the efferent arteriolar flow changed, although there was a tendency for both to decrease.(ABSTRACT TRUNCATED AT 250 WORDS)

Experiments were performed to investigate the effect 2-wk prior nephrectomy has on the recovery from a 40-min renal artery occlusion. Two groups were initially examined. Group 1 animals underwent sham nephrectomy and group 2 animals right nephrectomy 14 days prior to a 40-min left renal artery clamp. The percent recovery of inulin clearance in group 2 (33 +/- 6%) was not significantly different from that in the group 1 (36 +/- 8%) when measured 3 h after reflow. At 24 and 48 h of reflow, however, group 2 animals had a significantly higher percent recovery of inulin clearance (24 h: 31 +/- 5%; 48 h: 50 +/- 11%) than group 1 animals (24 h: 1 +/- 1%; 48 h: 8 +/- 4%). Similarly the histology was better preserved at 24 and 48 h in group 2. To further investigate this enhanced recovery, three additional groups were studied. Group 3 underwent right nephrectomy at the time of renal artery occlusion. Group 4 had right uretero-venostomies created immediately prior to the ischemic insult, and group 5 had their aortas rather than left renal arteries clamped. Each group shared with group 2, ischemia to all functioning excretory tissue. The percent recovery of inulin clearance in group 3 (48 +/- 9%), group 4 (54 +/- 5%), and group 5 (42 +/- 6%) were each significantly (P less than 0.005) higher than in group 1 (8 +/- 4%) when measured at 48 h. We conclude that the protection offered by uninephrectomy is not a consequence of hypertrophy but that alterations in the environment which follow ischemia to all functioning excretory renal tissue are responsible for the enhanced recovery seen.

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With micropuncture techniques, the present study examined the delivery of chloride to the superficial late distal tubule and the base and tip of the papillary collecting duct in rats treated with either Wy 47663, a synthetic analogue of atrial natriuretic peptide (ANP), or vehicle alone. Whole kidney glomerular filtration rate (GFR) and single-nephron glomerular filtration rate were not significantly different between the two groups. Late distal tubule chloride delivery was also not different between ANP- (5.71 +/- 1.15%) and vehicle- (6.28 +/- 1.12%) treated animals. However, fractional delivery to the base of the papillary collecting duct was significantly greater in the ANP-treated rats (14.37 +/- 1.98%) compared with vehicle-treated rats (7.32 +/- 1.47%). Tip papillary collecting duct delivery was also significantly greater in the ANP-treated rats (1.97 +/- 1.96 vs. 3.09 +/- 0.60%). In addition, the percent of chloride delivered that was reabsorbed along the papillary collecting duct was significantly less in the ANP-treated rats. In conclusion, ANP inhibits reabsorption in some tubular segments between the superficial late distal tubule and papillary collecting duct base as well as in the accessible portion of the papillary collecting duct.

Description is given of six body-builders who had been taking Methandrostenolone (up to 20 mg/day in intermittent courses for a year or more). At the time of examination there was no subjective disturbance of sexual function, but testosterone levels were low relative to laboratory standards and luteinizing hormone levels were also reducedparticularly in relation to testosterone concentrations. Abnormal liver function tests were seen in three of the six subjects, and one had mild diabetes with high serum cholesterol, triglycerides and uric acid. The weight gain of the group was not outstanding, and the only possible positive finding was a high haemoglob.in and haematocrit in one of the six subjects.