Effects of rehmanniae radix water extract on renal function and renin secretion rate in unanesthetized rabbits

This study was undertaken to explore the effects of different preparations of Rehmanniae Radix on renal function and renin secretion rate. Steamed Rehmanniae showed a decrease in urine volume, renal hemodynamics, and urinary excretion of electrolytes confined to the infused kidney, and was followed by an increase in urinary excretion of electrolytes from both kidneys. Dried Rehmanniae showed a decrease in urine volume, glomerular filtration rate, and urinary excretion of electrolytes, while raw Rehmanniae showed only an increase in urinary excretion of electrolytes. Steamed Rehmanniae and dried Rehmanniae decreased renin secretion rate, but raw Rehmanniae tended to increase renin secretion. These results suggest that the Rehmanniae Radix preparations have different effects on renal function and renin secretion rate.