| Abstract: | These studies provide evidence for the presence of a microsomal ethanol oxidizing system in rat Leydig cells. Activity of the microsomal ethanol oxidizing system in Leydig cells was 47.4 +/- 4.1 nmol acetaldehyde per 20 min per mg protein, while activity in crude interstitial cells was 26.0 +/- 5.4 nmol. This suggests that among cells comprising interstitial cells, activity is concentrated in Leydig cells. Activity was linear with respect to protein concentration and incubation time. The highest specific activity was observed in the microsomal fraction. The most effective cofactor was NADPH. The apparent Km for ethanol was 4 mM, suggesting that this system could effectively metabolize ethanol at concentrations found in the blood of males who drink. The apparent Km for NADPH was 11 microM. The activity in Leydig cells was unaffected by 4-methylpyrazole or potassium cyanide, which inhibit alcohol dehydrogenase and catalase activities, respectively. These data provide strong evidence for an enzyme system in Leydig cell microsomes which is capable of metabolizing ethanol. |
