[The participation of neurotransmitters in the regulation of the motor activity of the chick embryo amnion]

Abstract

The authors' data on time-related changes in the contractile activity of non-innervated smooth muscle amnion of the chick embryo devoid of blood vessels and on involvement of the amniotic fluid neurotransmitters in regulation of the amnion motor activity have been summarized. A scheme of possible mechanism underlying regulation of the spontaneous rhythmic contractile activity of the amnion by two antagonistic neurotransmitters present in the amniotic fluid: serotonin and noradrenalin, which stimulate and inhibit the amnion motor activity, respectively. The results of experiments on successive block of the serotonin and adrenergic 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 involvement of this humoral mechanism in the inhibitory effect of increased carbon dioxide content of the air on the amnion motor activity has been considered.