Amlodipine Corrects Changes in Blood Pressure and Baroreceptor Reflex Sensitivity in Sprague Dawley Rats Fed a High Salt Diet

Summary: High dietary salt ingestion causes elevated blood pressure both in humans and in experimental animals. Following reports that Calcium Channel Blockers may exhibit differences in the response of blood vessels to pressor agents, this study sought to test the effects of amlodipine on blood pressure (BP) and baroreceptor reflex sensitivity (BRS) responses to high salt ingestion. Three groups of weanling Sprague-Dawley rats i.e. control rats (CR), salt loaded rats (SR) and salt loaded rats concomitantly administered orally with amlodipine (SR+Am) were used. At the end of 6-week experimental period, terminal arterial BP was determined from one femoral artery. BRS was calculated from the change in heart rate per change in mean arterial BP following bilateral carotid artery occlusion. Plasma sodium and potassium ion concentrations were also determined. Results show that dietary salt loading in SR significantly increased systolic and diastolic BP and Na⁺ concentration but decreased BRS and K⁺ concentrations significantly. These changes were abolished in the (SR+Am) rats indicating the ability of amlodipine to ameliorate the increase in blood pressure, reduction in baroreceptor reflex sensitivity and alterations in plasma Na⁺ and K⁺ levels that were observed in SD rats fed a high salt diet.