[Effect of prodigiozan and pyrogenal on the neural regulation of the frog heart].

The action of bacterial lipopolysaccharides (pyrogenal and prodigiosan) on nervous regulation of the frog heart was studied. Both the substances provoked a considerable increase in the arrest of spontaneous contractility of the atria during stimulation of the extracardial nerves. This effect did not occur after atropine administration, but became manifest during the benzohexonium-induced blockade of conduction in the intracardiac ganglia. The bacterial lipopolysaccharides did not alter acetylcholinesterase activity or myocardial sensitivity to acetylcholine. It is assumed that variation of the nervous regulation of the heart under the effect of prodigiosan and pyrogenal is determined by the effect of these substances on the transmitter release from the presynaptic endings of the extracardial ganglia.