Effect of 3-hydrazino-6[N, N-bis (2-hydroxyethyl) amino]-pyridazine (L 6150) on renin in hypertensive rats.

L 6150 is an antihypertensive drug classified as a vasodilator. We have reported its antihypertensive effect observed in three different models of experimental hypertension, spontaneously hypertensive (SHR) rats, deoxycorticosterone and salt hypertensive (DOC) rats and two kidney, one clip hypertensive (CLIP) rats (1). The effects of hydralazine and ecarazine, widely used antihypertensive vasodilator drugs, were also determined for comparison. In the present study, we report the effect of long-term treatment with L 6150 and other drugs on plasma and kidney renin activities (PRA and KRA). Plasma and kidney samples were obtained from the rats used in the series of experiments reported in our previous paper (1). Briefly, rats of each model of experimental hypertension were separated into 5 groups and treated orally with one of the following drugs : H2O (SOL), L 6150 at doses of 4 (L4) or 12 mg/kg (L12), hydralazine at dose of 4 mg/kg (HZ) or ecarazine at dose of 12 mg/kg (EZ) per day, 5 days per week for 11 weeks. At the end of experiment 0.5 ml of blood sample was obtained through the cannula inserted into the abdominal aorta. The kidney was excised and weighed. Plasma and kidney samples were kept frozen at -20°C until the assay. PRA was determined by a modification of the method reported by