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 bl ood pressure (MAP), cardiac output (CO), peripheral resistances (TPR) and blood flow distribution in spontaneously mildly hypertensive femal e Wistar 30-34 months old rats. Under pentobarbital anesthesia, CO and regional organ blood flow were measured by the radioactive microspher es method, before and 30 min after administration of felodipine 0.5 mu mol/kg b. w. by gastric gavage. They were compared to the correspondi ng values in normotensive rats of the same strain and age. Fifteen (fr om twenty five) rats were hypertensive with a MAP averaging 139 +/- 2 mm Hg. CO and TPR were slighly higher in these hypertensive rats. Cere bral blood flow (CBF) was lower, though the difference did not reach s ignificant values. MAP significantly decreased after felodipine with n o significant changes in CO ant TPR in hypertensive as well as in norm otension 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 chan ges in CBF but a significant increase in portal venous inflow (PVI) in hypertensive rats only. In conclusion, in old female rats with mild s pontaneously hypertension, acute felodipine oral administration reduce d arterial blood pressure without diminishing CBF.