Decreased inositol 1,4,5-trisphosphate-specific binding in platelets from alcoholic subjects

We measured the degree of inositol 1,4,5-triphosphate (IP3)-specific binding in platelets from alcoholic and nonalcoholic subjects. IP3-specific binding in alcoholic subjects was 45% less than that in nonalcoholic subjects. There was no significant difference in the number of IP3 receptors as detected immunologically in the platelet membrane fractions from alcoholic and nonalcoholic subjects. These results indicate that the decrease in IP3-specific binding in alcoholic subjects may have been due to a decreased affinity, but not number, of IP3 binding sites. In contrast to the decrease in IP3 receptor binding, there were no significant changes in phospholipase-C activity or immunoreactivity of phospholipase C-β1 in platelet membranes from alcoholic subjects. The decreased IP3-specific binding in platelets may allow for the development of biological markers for alcoholism.