The Effects of Ocimum Gratissimum Leaf Extract on Cardiovascular and Renal Function in Rats

Abstract

The effects of Ocimum gratissimum leaf, a local food spice and traditional herbal remedy, on cardiovascular and renal function were studied in Sprague-Dawley rats. The rats were administered with crude ethanolic extract of the leaf of Ocimum gratissimum, orally over five weeks. At the end of the period the blood pressure, heart rate, packed cell volume (PCV), creatinine clearance, plasma urea and electrolyte concentrations (Na+ and K+) were measured. Also determined were the urine output, urine flow rate and urinary excretion of electrolytes (Na+ and K+). Some of the rats were sacrificed at the end of 5 weeks and dissected. The kidneys and urinary bladder were excised for studies of cortical histopathology and smooth muscle activity respectively. Age matched rats given normal saline over the same period acted as controls. Results are presented as means ± Standard error of the mean (SEM). Chronic Ocimum gratissimum administration increased systolic and diastolic blood pressure, heart rate and packed cell volume in the rats (P<0.001). Plasma Na+, K+ and urinary K+ levels increased (P<0.01) while urine Na+ levels decreased (P<0.01). There was a decrease in creatinine clearance (GFR) (P<0.05) and urine output (P<0.05). The urine flow rate was not significantly different between the treated rats and the control rats. Ocimum gratissimum caused a reduction of 50% in the maximum contraction induced by acetylcholine in the bladder smooth muscle (EC50, 0.2mg/ml), thus suggesting that the extract may possess anticholinergic properties. No significant histological changes were observed in renal cortical tissue of O. gratissimum treated rats. These results show that Ocimum gratissimum increased cardiovascular function and urinary electrolyte reabsorption and reduced GFR. Thus suggesting activation of sympathetic and renin-angiotensin-aldosterone mechanisms. The increase in packed cell volume may indicate an increase in haematopoiesis probably due to activity of renal erythropoietic factor.

NQJHM Vol. 16 (2) 2006: pp. 60-65