1. The effects of chronic dietary salt-loading and nifedipine therapy on hypertension-prone (SBH), -resistant (SBN) and parental (SB) Sabra rats were investigated. Salt diet for 12 weeks resulted in a sustained hypertension and heart hypertrophy only in SBH.
2. Nifedipine therapy (300 p.p.m. = 300 mg/kg of food) introduced after week 7 on a salt diet, achieved small changes in salt-loaded SBN and SB rats, but resulted in a marked decrease in blood pressure in SBH rats within 1 week and in a regression of cardiac hypertrophy.
3. Plasma renin activity rose slightly in nifedipine treated SB and SBN rats, but decreased significantly in treated SBH rats.
4. Histopathological investigations revealed hypertensive vasculopathy in three out of nine untreated SBH rats, whereas there were no morphological changes in the treated rats.