1982 Volume 79 Issue 10 Pages 1935-1943
Serum γGTP activity is known as a sensitive marker for the detection of alcoholism, but the mechanism of its elevation remains to be elucidated. Since intestinal tissue contains considerable amount of γGTP, we wondered if intestinal γGTP activity is affected by ethanol, contributing to the elevation of serum γGTP activity. To that effect, male rats were pair-fed by nutritionally adequate liquid diet containing either ethanol (36% of cal.) or isocaloric carbohydrate (controls.) After 6 weeks ethanol feeding, serum γGTP activity was moderately increased. Moreover, intestinal γGTP activity was enhanced by 46% expressed per gram of intestinal mucosa. After ethanol, increased γGTP activity was found histochemically in brush-border and submucosal lymphatics. Furthermore, electronmicroscopic observation revealed that intestinal γGTP was localized in plasma membrane and endoplasmic reticulum. To further analyse possible contribution of intestinal γGTP to serum enzyme activity, we introduced cannula into intestinal lymphatic channel near cisterna chyli and lymph was collected continuously for up to 4 hours. In ethanol-fed rats, intestinal lymph γGTP concentration increased by 83% and this was more than doubled when expressed as output per hour. Moreover, diversion of intestinal lymph resulted in a significant decrease in serum γGTP activity. These results suggest that enhanced intestinal γGTP activity contributes, at least partly, to the elevated serum enzyme activity after ethanol.