Parameters of cardiac activity after administration of the cholinesterase inhibitor physostigmine were analyzed in newborn rats and on day 16 of postnatal development. The type of cardiovascular response to acetylcholine excess in newborns and 16-day-old rats were similar, but they significantly differed by the magnitude, which suggests that that maturation of cholinergic structures involved in the regulation of cardiac activity is completed during the early postnatal ontogeny.

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On newborn rat pups, for the first day after birth, there was studied the character of mutual influences between the slow-wave rhythmical components of the cardiac, respiratory, and motor activities reflecting interactions between the main functional systems of the developing organism.The study was carried out in norm and after pharmacological depression of the spontaneous periodical motor activity (SPMA) performed by narcotization of rat pups with urethane at low (0.5 g/kg, i/p) and maximal (1 g/kg, i/p) doses. Based on the complex of our obtained data, it is possible to conclude that after birth in rat pups the inter-systemic interactions are realized mainly by the slow-wave oscillations of the near-and manyminute diapason. The correlational interactions mediated by rhythms of the decasecond diapason do not play essential role in integrative processes. Injection to the animals of urethane producing selective suppression of reaction of consciousness, but not affecting activating influences of reticular formation on cerebral cortex does not cause marked changes of autonomous parameters, but modulates structure and expression of spontaneous periodical motor activity. There occurs an essential decrease of mutual influences between motor and cardiovascular systems. In the case of preservation of motor activity bursts, a tendency for enhancement of correlational relations between the modulating rhythms of motor and somatomotor systems is observed. The cardiorespiratory interactions, more pronounced in intact rat pups in the near-and manyminute modulation diapason, under conditions of urethane, somewhat decrease, whereas the rhythmical components of the decasecond diapason-are weakly enhanced.

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