Chronic treatment with captopril, SQ29,852, hydralazine and a 33% fish meal diet in malignant stroke-prone spontaneously hypertensive rats.

Malignant stroke-prone spontaneously hypertensive rats (M-SHRSP) are a useful animal model for studying juvenile malignant hypertension. Using M-SHRSP males, the effects of SQ 29,852 [(S)-1-[6-amino-2-[[hydroxy (4-phenylbutyl) phosphinyl]oxy]-1-oxohexyl]-L-proline; 30-40 mg/kg per day], captopril (30-40 mg/kg per day), hydralazine hydrochloride (10-15 mg/kg per day) and a 33% fish meal diet on the prevention and therapy of malignant hypertension were examined. Drugs and diet were given separately, beginning at weaning, maturity or adulthood. Observed effects included antihypertension, prolonged life span and prevention and/or reversal of angionecrosis. Each treatment resulted in an antihypertensive effect, but some adult rats seemed treatment-resistant. SQ 29,852 was the most effective treatment for reducing blood pressure. The life span of animals in the treated groups was extended significantly beyond that of the controls. In particular, those rats treated with either captopril or SQ 29,852 lived in excess of 500 days. This included not only those in which treatment resulted in a lowering of blood pressure, but also those whose severe hypertension was not so reduced. Angionecrosis was observed in the organs of many of the non-treated animals, including the brain, heart, kidneys and testes. Both hydralazine and the fish meal diet had a limited effect, if any, on the prevention or reversal of angionecrosis. In contrast, almost none of the rats given either captopril or SQ 29,852 showed cerebrovascular lesions or angionecrosis of the brain, heart and kidneys; angionecrosis in adult M-SHRSP kidneys disappeared within 10 or 18 days after the initiation of SQ 29,852 or captopril, respectively. This data seems to support a possible role for these two drugs not only in prevention, but also in repair, of angionecrosis independent of markedly high blood pressure in M-SHRSP. Based on our overall observations, SQ 29,852 was seen as the most effective of the treatments studied.