Experimental hypertension induced by 19-nor-progesterone treatment in the rat

Fifty-day-old unilaterally nephrectomized and 1% saline-drinking Sprague-Dawley CD male rats were divided into three comparable groups on the basis of blood pressure, body weight, and fluid intake. The control group received vehicle only, the second group received 19-nor-progesterone [19-nor-pregn-4-ene-3,20-dione (19-Nor-Prog)] in a dose of 250 micrograms/24 h, and the third group received aldosterone-acetate (Aldo-Ac) in a dose of 125 micrograms/24 h, by means of Alzet osmotic minipumps implanted sc for 21 days. Both the 19-Nor-Prog- and the Aldo-Ac-treated rats became hypertensive to a similar degree in the course of the study. Rats given Aldo-Ac also developed polydipsia, decreased body weight, cardionephromegaly, and hypokalemia. The 19-Nor-Prog-treated rats showed no significant changes in heart and kidney weights. The hypertensinogenicity of 19-Nor-Prog is unrelated to significant changes in heart and kidney weight, as is the case with potent mineralocorticoids.