Effects of Hypoxis hemerocallidea (Fisch & CA 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 center dot 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 mu g center dot h(-1) in separate groups of rats during the treatment period. For chronic studies, individually caged rats were administered twice with APE (30 mg center dot kg(-1) PO) every third consecutive day at 09h00 and 17h00 for 5 weeks. Control rats received distilled water (3 mL center dot 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 center dot min(-1) vs. 1.52 +/- 0.02 mL center dot min(-1)) and increased plasma creatinine concentration ( 55 +/- 3 mu mol center dot L-1 vs. 68 +/- 6 mu mol center dot L-1). The results from this study suggest that the H. hemerocallidea corm aqueous extract may impair kidney function.