Antihypertensive Activity of the Aqueous Extract of Retama raetam Forssk. Leaves in Spontaneously Hypertensive Rats

The antihypertensive and diuretic effects of the aqueous extract of Retama raetam Forssk. (RR) leaves were studied in both normotensive (WKY) and spontaneously hypertensive rats (SHR). In SHR rats, daily oral administration of RR (20 mg/kg) for three weeks exhibited a significant reduction in blood pressure. The systolic blood pressure decreased significantly from the seventh day (P<0.01) and persisted through the end of treatment (P<0.001) in SHR rats. The RR significantly enhanced the diuresis in WKY rats (P<0.001). Furthermore, oral administration of RR at a dose of 20 mg/kg produced a significant increase on urinary excretion of sodium (P<0.05), potassium (P<0.01) and chlorides (P<0.01) in SHR rats. In WKY rats, RR treatment induced a significant increase on urinary potassium elimination (P<0.05) without affecting sodium and chloride excretion. Irbesartan (Avapro(r)) 20 mg/kg (body weight), an angiotensin II receptor antagonist, was used as reference drug. No significant changes were noted in heart rate after RR treatment in SHR as well as in WKY rats. Glomerular filtration rate showed a significant increase after RR administration in WKY rats (P<0.01) and a no significant increase in SHR rats. These results suggest that oral administration of aqueous RR extract exhibited antihypertensive and diuretic effects in SHR rats and diuretic action in WKY rats.