(R)-mevalonate excretion in human and rat urines.

(R)-Mevalonate was identified by radioenzymatic assay in human and rat urines. This was confirmed by spectrophotometric enzymatic assay of an ether extract of human urine. The average excretion rate of (R)-mevalonate in humans was 1.7 mumol/24 hr which corresponds to 29% of the glomerular filtration rate. In anesthetized rats the average rate of (R)-mevalonate excretion was 350 pmol/min, corresponding to 44% of the glomerular filtration rate. These rates were not affected by the sex of the subjects or animals. After bilateral nephrectomy, the concentration of (R)-mevalonate in rat serum increased within 2 hr to a new level that was 5 times that of sham-operated controls. Nephrectomized rats showed a decrease in their tolerance to an intravenous load of mevalonate. These data show that (R)-mevalonate is normally excreted in the urine of humans and rats. Urinary excretion of (R)-mevalonate should therefore be taken into account in in vivo studies on the metabolism of this compound.