INVOLVEMENT OF NEUROTRANSMITTERS IN REGUL ATION OF THE MOTOR-ACTIVITYOF THE CHICK-EMBRYO AMNION

The authors' data on time-related changes in the contractile activity of non-innervated smooth muscle amnion of the chick embryo devoid of b lood vessels and on involvement of the amniotic fluid neurotransmitter s in regulation of the amnion motor activity have been summarized. A s cheme of possible mechanism underlying regulation of the spontaneous r hythmic contractile activity of the amnion by two antagonisfic neurotr ansmitters present in the amniotic fluid: serotonin and noradrenalin, which stimulate and inhibit the amnion motor activity, respectively. T he results of experiments on successive block of the serotonin and adr energic receptors by introduction of the corresponding antagonists in the chick embryo amniotic fluid speak in favor of the proposed scheme of humoral regulation of the amnion motor activity. A possible involve ment of this humoral mechanism in the inhibitory effect of increased c arbon dioxide content of the air on the amnion motor activity has been considered.