Effect of felodipine on systemic hemodynamics of spontaneous mild-hypertensive aged rats

The aim of the present study was to examine the effects of felodipine, a dihydropyridinic calcium ions channels blocker, on mean arterial blood pressure (MAP), cardiac output (CO), peripheral resistances (TPR) and blood flow distribution in spontaneously mildly hypertensive female Wistar 30-34 months old rats. Under pentobarbital anesthesia, CO and regional organ blood flow were measured by the radioactive microspheres method, before and 30 min after administration of felodipine 0.5 mumol/kg b. w. by gastric gavage. They were compared to the corresponding values in normotensive rats of the same strain and age. Fifteen (from twenty five) rats were hypertensive with a MAP averaging 139 +/- 2 mm Hg. CO and TPR were slightly higher in these hypertensive rats. Cerebral blood flow (CBF) was lower, though the difference did not reach significant values. MAP significantly decreased after felodipine with no significant changes in CO and TPR in hypertensive as well as in normotensive animals. Renal blood flow (RBF) was similar before and after felodipine which significantly decreased renal vascular resistance in both groups. Felodipine administration did not induce significant changes in CBF but a significant increase in portal venous inflow (PVI) in hypertensive rats only. In conclusion, in old female rats with mild spontaneously hypertension, acute felodipine oral administration reduced arterial blood pressure without diminishing CBF.