Diuretic activity and toxicity study of the aqueous extract of Cola nitida seed on markers of renal function and electrolytes in rats

Abstract Background Cola nitida is a plant, conventionally used in Africa in the treatment of various ailments such as migraine, morning sickness and indigestion. The aim of the present study was to explore the diuretic activity of the aqueous extract of C. nitida seed (AECONS) and alteration caused by its subchronic administration on the structure and function of the kidney of male Wistar rats. Methods The study was divided into diuretic and subchronic studies. Twenty-five male Wistar rats weighing between 140 and 180  g were divided into five groups of five rats each. The first 24 h of this study investigated the possible diuretic activity of C. nitida seed. Group I (the control) received 25 mL/kg of normal saline. Group II (the standard) received 20 mg/kg/day of furosemide. Groups III, IV, V received 400, 600 and 800 mg/kg/day of AECONS, respectively, and orally. Urine volume, pH, specific gravity and electrolytes were estimated in the samples of urine collected after 6 h of the study. From the second day onward and up to a period of 4 weeks, the rats in each group were given normal saline, furosemide and AECONS once daily as was done on the first day. At the end of the 4-week treatment period, blood and urine samples were collected for the determination of creatinine, urea, Na + , K + and Cl − concentrations. Results The results of the diuretic study showed that the AECONS at all doses used and furosemide produced a significant increase in urine output with respect to the control group. AECONS also induced a significant increase in the urine concentrations of Na + , K + , Cl − in the experimental and standard groups when compared with the control group, except for group III which showed no significant variation in K + concentration. In the subchronic study, AECONS caused a significant increase in the urine levels of Na + , K + , Cl − in the experimental and standard groups when compared with the control rats. The plasma Na + concentration of groups IV and V was significantly lower than that of the control group. Photomicrographs of the kidneys of the experimental and standard groups revealed no significant alterations in the histology of their kidney tissues. Conclusions It is concluded that AECONS induced diuresis which is associated with increased Na + , K + and Cl − loss in rats without any significant alteration in the structure of their kidneys.