Quantitative histochemical study of a vitamin E analog on rat gastric cyclic AMP

The vitamin E analog, 2,2,7,8-tetramethyl-5,6-orthoquinonechroman, unlike vitamin E itself, had been reported to be a potent inhibitor of beef liver cyclic AMP-PDE in vitro (about 3.5 times more inhibitory than theophylline under the same conditions). In this in vivo study, single intraperitoneal injections were given to fasted rats, 15 min before killing, of a solution of 20, and of a suspension of 130, mg analog/kg in 4% ethanol. No significant increases over the 4% ethanol control values in cyclic AMP levels were produced in any of the histological regions of the glandular stomach. However, injection of the 4% ethanol itself produced a rise of about 50% (peak value 4.1 pmoles/mg wet wt, 0.16 pmoles/mug protein-nitrogen) in the cyclic AMP concentrations in the parietal cell region and had no significant effect in any of the other histological zones where the concentrations were much lower.