Effect of chronic ethanol feeding on intestinal alkaline phosphatase activity in rats

The effect of chronic ethanol feeding has been studied on intestinal alkaline phosphatase (IAP) activity. The enzyme was assayed using p-nitrophenyl phosphate (PNPP), phenylphosphate (PhP) and beta-glycerophosphate (beta GP) as the substrates. Feeding of ethanol for 10 days did not effect the enzyme activity but it was markedly elevated in animals fed ethanol for 20 or 30 days. However, ethanol administration to rats, for over 6 wk exhibited a decline in IAP activity, both in the soluble and membrane fractions of intestine. Kinetic studies revealed an enhancement in Vmax with no change in apparent Km after 30 days of ethanol feeding and a decrease in Vmax after 6 wk of ethanol ingestion. These results were confirmed by assaying the enzyme activity in non-denatured polyacrylamide gels using 5-bromo-4-chloro-3-indoly1 phosphate (BCIP) as the substrate. These findings suggest differential changes in IAP activity in response to ethanol feeding in rats.