Effects of Hypoxis hemerocallidea (Fisch. & C.A. Mey.) [Hypoxidaceae] corm (African Potato) aqueous extract on renal electrolyte and fluid handling in the rat.

Current biomedical evidence suggests that Hypoxis hemerocallidea (Fisch. & C.A. Mey.) [Hypoxidaceae] (African Potato [AP]) corm extract may be useful in the management of type 2 diabetes mellitus. However, more recent reports have also indicated that certain herbal extracts attenuate the deterioration of kidney function in diabetes mellitus. Accordingly, this study investigated the effects of short- (acute) and long-term (chronic) administration of H. hemerocallidea corm aqueous extract (APE) on renal fluid and electrolyte handling in male Wistar rats. Acute effects of APE were investigated in separate groups of anesthetized rats challenged with a continuous jugular infusion of 0.077 M NaCl at 9 mL x h(- 1). After a 3.5-h equilibration period, consecutive 30-min urine collections were made over the subsequent 4 h of 1-h control, 1.5-h treatment, and 1.5-h recovery periods for measurements of urine flow, Na+, and K+ excretion rates. To establish the effects of acute APE, the extract was added to the infusate at doses of 90, 180, or 360 microg x h (-1) in separate groups of rats during the treatment period. For chronic studies, individually caged rats were administered twice with APE (30 mg x kg (-1) PO) every third consecutive day at 09h00 and 17h00 for 5 weeks. Control rats received distilled water (3 mL x kg(-1)). Urine volume and total urinary outputs of creatinine, Na+, and K+ were determined from 24-h samples. Acute infusion of APE produced a dose-dependent, significant (p < 0.01) decrease in urine flow, K+, and Na+ excretion rates. Chronic APE treatment significantly reduced urinary Na+ output between weeks 2 and 5, without affecting either urine flow or K+ excretion rates. When compared with control animals, APE significantly reduced GFR (2.54+/-0.09 mL x min (-1) vs. 1.52+/-0.02 mL x min (-1)) and increased plasma creatinine concentration (55 +/- 3 micromol x L(-1) vs. 68 +/-6 micromol x L(-1)). The results from this study suggest that the H. hemerocallidea corm aqueous extract may impair kidney function.