[Mechanism of the intracardiac interactions of the vagus and sympathetic nerves: is a serotoninergic mechanism possible?].

A study was made of the conditions of the occurrence and mechanisms of the enhancement by the sympathetic nerve of the vagus-induced inhibition of rabbit heart work. It was discovered that to obtain such a phenomenon, it is necessary that stimulation of the stellate ganglion be made in the presence of perithreshold stimulation of the vagus after blockade of beta-adrenoreceptors. The inhibitory effect was not abolished by dihydroergotoxin but was blocked by promedol, aminazine and diprazine. It is suggested that the serotoninergic component is involved in the mechanism of the enhancement of the vagus-induced inhibition that occurs during stimulation of the sympathetic nerve.