Effects of pildralazine alone and in combination on severe hypertension and cerebrovascular lesions in saline-drinking spontaneously hypertensive rats.

The efficacy of long-term treatments with the vasodilator antihypertensive pildralazine alone and in combination with propranolol or dihydrochlorothiazide in preventing blood pressure increase and cerebrovascular lesions in saline-drinking spontaneously hypertensive rats (SHR) was evaluated. Groups of 20-40 animals were treated daily for 13 weeks. At the end of the experiments the brains were examined histologically and vascular lesions, ranging from arterial wall damage to cerebral infarction, were checked. In the control groups (n = 60), systolic blood pressure gradually rose to over 200 mmHg, and about 74% of the animals had lesions. Pildralazine at a dose of 1 mg/kg p.o. significantly inhibited the onset of severe hypertension; the combination of pildralazine with moderately effective doses of propranolol (10 mg/kg p.o.) or dihydrochlorothiazide (5 mg/kg p.o.) completely prevented the blood pressure increase. When blood pressure control was achieved, the incidence of cerebrovascular lesions was also significantly reduced.