Effects of nifedipine on blood pressure and heart rate in conscious neurogenic hypertensive rats.

The effects of nifedipine (15 micrograms/kg, i.v.) on mean blood pressure (MBP) and heart rate were studied in neurogenic hypertensive rats (NHR), compared with renovascular hypertensive (RHR), and control (CR) rats. The maximal MBP reduction reached 32, 37 and 9%, respectively. The baseline MBP was recovered after 120, 150, and 5 min, respectively. The hypotension was not accompanied by changes in the baseline high heart rate of NHR and by tachycardia in CR and RHR groups. The data show the antihypertensive efficacy of nifedipine in both models of hypertension and indicate that under conditions of increased sympathetic tone the cardiac pacemaker cannot be easily inhibited by nifedipine.