Investigation of the presence of "renopressin" in kidney extracts from rabbits and rats.

One-kidney, one clip hypertension may be caused by a renal humoral factor that is not renln. In the search for such a factor, Skeggs and coworkers have provided evidence that certain extracts of rabbit kidneys can increase the blood pressure of other rabbits Indefinitely by a mechanism having a slow onset. In the present experiments an ethanol extract of rabbit kidneys and an acetone extract of a 2.0-4.0 M ammonium sulfate precipitate were injected into rabbits for 10 to 12 days. By Day 3 the Increase in blood pressure (mm Hg) was only 1 ± 3 and 7 ± 2, respectively, but by the end of the injection period, blood pressure had increased by 21 ± 4 (p < 0.025) and 19 ± 4 {p < 0.005). Several weeks later the blood pressure was still significantly elevated above control: 13 ± 2 (p < 0.005) and 15 ± 5 (p < 0.05). A similar pattern of response was seen in unilaterally nephrectomized rabbits. In contrast, injection of an ethanol extract of rat kidneys or a 0.75-2.0 M ammonium sulfate fraction or a 2.0-4.0 M ammonium sulfate fraction or an acetone extract of the latter had no effect on the blood pressure of rats when injected at comparable doses for 13 to 15 days. The ethanol extract of rabbit kidneys caused a mild increase in the blood pressure of rats, but this was not significant. No increase in blood pressure was seen when renal cells from rats with one-kidney, one clip hypertension were Injected lutraperitoneally into normal rats. Therefore, although the present experiments support the existence of renopressin in rabbit kidneys, a similar factor could not be demonstrated in extracts of rat kidneys. (Hypertension 4: 198-204, 1982)