CHOLINE ACETYLTRANSFERASE ACTIVITY IN GUINEA‐PIG HEART IN VITRO
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TL;DR
The results demonstrate the feasibility and specificity of measuring the differences in choline acetyltransferase activity in dialysed homogenates prepared from the four chambers of the heart.
Abstract
Abstract— Choline acetyltransferase (EC 2.3.1.6) catalyses the following reversible reaction: acetyl coenzyme A + choline acetylcholine + coenzyme A. Enzyme activity in the atria and ventricles of guinea‐pig heart varied independently of the biochemically related carnitine acetyltransferase (EC 2.3.1.7). Choline acelyltransferase activity was greatest in right atrium, intermediate in right ventricle and left atrium and lowest in left ventricle (405. 2‐33. 177 and I 33 nmol min ‐1 g ‐1 , respectively). Carnitine acetyltransferasc activity was greatest in the right and left ventricle and least in the right and left atria (8‐86. 8‐27, 3‐18 and 2‐38 mmol min ‐1 g ‐1 . respectively). Carnitine acelyltransferase activity was 800‐ to 6000‐fold greater than that of the choline acetyltransferase. depending on the chamber. Bromoacctylcholine inhibited acetylcholine. but not acetylcarnitine biosynthesis in vitro. Contrariwise, acetylcarnitine inhibited carnitine, but not choline acetyltransferase. These results demonstrate the feasibility and specificity of measuring the differences in choline acetyltransferase activity in dialysed homogenates prepared from the four chambers of the heart.