THE INFLUENCE OF HEMICHOLINIUM NO. 3 AND VAGAL STIMULATION ON ACETYLCHOLINE CONTENT OF RABBIT ATRIA

The problem of the physiological role of acetyl-choline (ACh) in heart function gained new interest with the work of Bulbring and Burn (1949). These authors showed that atria which ceased to beat many hours after isolation may be stimulated by low concentrations of ACh. More-over, they demonstrated that ACh synthesis is inhibited in such atria and that it may be re-stored by exogenous ACh. The authors supposed that ACh is necessary for automatic cardiac ac-tivity and that it is synthesized by heart muscle. Milton (1959) showed that ACh content of isolated atria which ceased to beat is reduced to about 50 % as compared with fresh preparations. It was established in many experiments tha