Choline acetyltransferase activity in rat and guinea pig heart following vagotomy.

Choline acetyltransferase (CAT), which serves as a marker for the preganglionic and postganglionic parasympathetic cholinergic neurons in heart, was measured in heart regions in rats and guinea pigs after either a right or a left unilateral cervical vagotomy or a sham operation. One day after a left vagotomy in rat, CAT activity was decreased in the region of the SA and AV nodes. In rats killed on the 2nd, 4th, and 8th day after left vagotomy, the activity of CAT in these regions increased to the control level. CAT activity in the remainder of the heart did not decrease. In guinea pig 1 wk after a left vagotomy, CAT activity was decreased in the anterior interventricular septum but not in other regions. Selective increases in enzyme activity were noted in the right atrial appendage following left vagotomy and in the superior interventricular septum following right vagotomy. These results suggest that compensatory increases in CAT activity occur that may be related to collateral sprouting similar to that observed in the frog heart.