Abstract
In male Wistar rats, 1α-HCC and 1α, 25-DHCC induced diuretic effects in doses of 2.5 and 25μg/kg p.o., while no such effects of 1α-HCC were seen with a dose of 0.25 μg/kg p.o. Effect of 1α-HCC appeared later than that of 1α, 25-DHCC, but at 24 hr, the difference disappeared. Similar results were obtained with urinary concentrations of calcium (increase) and phosphorus (decrease). Glomerular filtration rate (GFR) and tubular reabsorption of phosphate (TRP) were remarkably elevated by 1α, 25-DHCC, and effects of 1α-HCC were rather weak and apparently not dose dependent. In light of these results and the finding that there was no difference between the effects of 1α-HCC and 1α, 25-DHCC on serum calcium and phosphorus at 24 hr, the mechanism of action of these sterols on the renal function seems to differ. In male Beagle dogs, 0.25 μg/kg/day p.o. of 1α-HCC or 1α, 25-DHCC induced a severe hypercalcemia and GFR was decreased in the 1α, 25-DHCC treated group. A gradual recovery occurred with cessation of the administration. Thus decrease in GFR was considered to be due to calcification of the kidney.
