The in vitro metabolism of mevalonate by sterol and nonsterol pathways in neonatal chick.

1. Incorporation of mevalonate into nonsaponifiable lipids by neonatal chick liver and kidney slices was studied as a function of weight of tissue and incubation time. In the same conditions, more nonsaponifiable lipids were produced in kidney than in liver. 2. CO2 production from mevalonate increased with the weight of tissue and with the incubation time. Over 80% of CO2 produced from mevalonate resulted from the shunt pathway in kidney, while in liver this route was quantitatively insignificant. 3. 2-14C from mevalonate was also incorporated into saponifiable (acidic) fraction by kidney slices. 4. Incorporation into nonsaponifiable lipids and total CO2 increased with the concentration of mevalonate. This increase was more pronounced in kidney than in liver especially at low mevalonate concentrations. In the presence of 0.1-8.0 mM mevalonate over 80% of the CO2 produced from this substrate resulted from the shunt pathway, while liver was practically ineffective whatever be the concentration of mevalonate. 5. The percentage of mevalonate metabolized in the kidney by shunt pathway increased with the incubation time and reached over 15% in the presence of 0.1-8.0 mM mevalonate.