Development of physiological responses to acetylcholine during organ culture of young embryonic chick hearts.
Young (3 days-old) embryonic chick hearts (i.e., prior to innervation) have a low sensitivity and transient response to acetylcholine (ACh). In the present experiments, in which the hearts were placed into organ culture for a period of up to 7 days, the sensitivity to ACh was found to increase with time in culture, and the inhibitory action of ACh persisted for a longer time (i.e., desensitization declined). Thus, the ability to ACh to slow spontaneous heart rate and to shorten action potential duration (in the atrium) became greater during the course of organ culture. The effects of ACh on spontaneous heart rate and on action potential duration were blocked by atropine. These results suggest that the physiological responses to muscarinic agonists in young embryonic chick hearts continue to develop in organ culture, and that the increased sensitivity to muscarinic agonists seen in ovo is unlikely to be due to the development of innervation.
D000109:Acetylcholine / Q000494:pharmacology*; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002642:Chick Embryo; D006321:Heart / Q000187:drug effects* / Q000294:innervation / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects; D009924:Organ Culture Techniques; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology
D011976:Receptors, Muscarinic; D001285:Atropine; D000109:Acetylcholine