[Establishment of somato-sympathetic reactions during the early stages of postnatal ontogeny in cats]. / Stanovlenie somato-simpaticheskikh reaktsii na rannikh étapakh postnatal'nogo ontogeneza koshek.

In adult cats and 1--16--day kittens, repeated stimuli of less than 1/sec and supramaximal strength applied to afferent fibers of nervus ischiadicus evoked the multicomponent responses recorded from efferent fibers of n. hypogastricus. Latencies of responses components decreased during postnatal development. In all the animals basic three responses remained unchanged after Th10-12 chordotomy. Stimulation of kittens afferent somatic fibers with frequency of 10/sec and of variable strength enhanced the sympathetic nerve activity and in rare occasions suppressed it. In adult animals the sign of sympathetic nerve response depended on the level of spontaneous sympathetic activity and on the stimulus strength. This relation remained unchanged after the chordotomy. In chordotomised kittens repeated stimuli applied to somatic nerve produced the sympathetic nerve activation alone.

[The effect of changes in the level of interoceptive afferentation on the spontaneous periodic motor activity of rat pups]. / Vliianie izmeneniia urovnia interotseptivnoi afferentatsii na spontannuiu periodicheskuiu motornuiu aktivnost' krysiat.

The effect of intraperitoneally injected (25 mg/kg) novocaine (procaine) on the spontaneous periodic motor activity was investigated in rat puppies ageing from 1 to 14 days. It was shown that reactions were phasic: initial continuous and then elevated activity was followed by depression and recovery. The duration and intensity of stimulation and depression decrease with age. It was concluded that in newborn animals an excitability of motor centers depends on the level of interoceptive afferentation. The last may be one of the motor activity regulation mechanisms. The role of this mechanism decreases with age in favour of extero- and proprioception mechanisms of motor control.

[The reflex and direct actions of novocaine on the rhythm of the heart beats in rats in early postnatal ontogeny]. / Reflektornoe i priamoe deistvie novokaina na ritm sertsebienii krys v rannem postnatal'nom ontogeneze.

In experiments on newborn rats it was shown that heart beating frequency depended on the intensity of interoceptive afferentation. Partial shutdown of the afferentation by means of intraperitoneal injection of novocaine in the dose of 25 mg/kg of body weight caused the increase of heart beating and the more complete one at higher doses (100 mg/kg of body weight) led to its decrease. The injection of 2% novocaine (150-200 mg/kg of body weight) into the peritoneum of rat puppies on the first week of life caused the transition of bradycardia into temporary or permanent stop of heart beating. The same effect was observed for isolated atrium of rat puppies on the first week of life after the addition of 0.1% novocaine to feeding solution. This effect disappeared in older animals. It was concluded that resorptive effect of novocaine on heart structures causing the disturbance of heart automatism in newborn rats occurred along with the reflex one.

[Water metabolism in monkeys during 14-day anti-orthostatic hypokinesia]. / Vodnyi obmen u obez'ian v protsesse 2-nedel'nogo prebyvaniia v usloviiakh antiortostaticheskoi gipokinezii.

Water balance parameters were measured in hypokinetic rhesus monkeys using tritiated water. During exposure the water content decreased by 18.4%, with 11.3% lost within the first 7 days. The rate of water renovation measured with respect to H3 half-life was decreased by a factor of 1.5 during the first week and increased by 10% during the second week, as compared to the pretest value. Daily water losses diminished by 30% during the first week and approached the pretest level during the second week. These findings are indicative of three phases in the time-course variations of water balance during head-down tilt.

[Age changes in rat vasomotor reflexes and sympathetic neuron ultrastructure following chemical sympathectomy]. / Vozrastnye izmeneniia vazomotornykh refleksov i ul'trastruktury simpaticheskikh neironov u krys posle khimicheskoi desimpatizatsii

Prolonged administration of guanethidine (20 mg/kg) to newborn rats caused a marked reduction in the number of cells in stellate ganglia. The administration of guanethidine for 14 days decreased the amount of cells to 30% of the normal (partial sympathectomy), and for 28 days--to 0.5% (complete sympathectomy). At the age of two months the blood pressure pressor reflexes to asphyxia and femoral nerve stimulation were absent in both groups of the sympathectomized animals. These responses, however, were restored in the partially sympathectomized animals at the age of four months. No restoration took place in the completely sympathectomized animals. The electron microscopic studies of neurons in the partially sympathectomized animals showed the presence of a great number of neurofibrils. According to literature data this fact was typical of cells in which an active growth of axon fibers took place.

[The growth of axons in the periphery after a decrease in the quantity of nerve cells in sympathetic ganglia]. / Rost aksonov na periferii posle umen'sheniia kolichestva nervnykh kletok v simpaticheskikh gangliiakh

The amount of cells in stellate ganglia of rat was decreased by chemical sympathectomy to 30% of the normal amount. At the age of two months sympathectomized rats have no pressor reflexes to asphyxia and femoral nerve stimulation. These responses are restored at the age of four months. The electron-microscopic and fluorescence-microscopic data show that the growth of axons in the remaining adrenergic neurons of sympathectomized animals takes place at the age between two and four months.