Effects of urecholine and atropine on canine pancreas slices. On incorporation of 14C-adenine and 14C-orotic acid into acid-soluble metabolites and RNA.

Abstract The incorporation of 8- 14 C-adenine into cytoplasmic and nuclear RNA of canine pancreas slices proceeds at a much faster rate than that of 6- 14 C-orotic acid. The drug, urecholine, inhibits the conversion of adenine into nuclear RNA. This inhibition is blocked by the cholinergic antagonist, atropine. The incorporation of labeled adenine or orotic acid into the acid-soluble pool of the tissue is likewise inhibited by urecholine, and this effect is also prevented by atropine. By means of thin-layer chromatographic separation of the components of the acid-soluble pool, it was shown that urecholine decreased the pool size of ATP and ADP whereas that of AMP was but very slightly decreased. Intracellular concentration of IMP was unchanged, but that of hypoxanthine was increased. The specific activities of ATP and ADP were moderately decreased, that of AMP was unaffected, but those of IMP and hypoxanthine were markedly increased. The amount and specific activity of hypoxanthine in the medium were increased. Atropine blocked the effect of urecholine on ATP and ADP pool size and concentration, but it resembled urecholine in increasing the specific activity of IMP. Atropine also blocked the effect of urecholine on hypoxanthine pool size and specific activity in both the tissue and the medium. Atropine, however, increased the pool size of IMP.