In surviving cuts of the hypothalamus, stimulation of the supraoptic nucleus induced focal potentials in the paraventricular nucleus. A repeated stimulation was followed by a reduction of the descending of the focal potentials. Tetanization of the supraoptic nucleus induced an additional wave at the descending phase of focal potentials preserving for 15 min. The data obtained suggest a functional plasticity of the hypothalamus paraventricular nucleus' cells.
Cerebral blood flow and the water content in the brain cortex were measured in rabbits with indwelling electrodes. Calcium antagonists increased the CBF in the motor area and decreased it in other regions of the brain.
: Bilateral infusion of 6-hydroxydophamine (15 mg/ml) into the n. accumbens and substantia nigra accelerated the avoidance conditioning and increased the dopamine and 3,4-dihydroxiphenylacetic acid levels in the striatum as compared with the rats which had only been injected the same agent in the substantia nigra alone. Infusion of this agent into the n. accumbens can be used to compensate for the nigrostriatal deficit.
A close interrelationship was demonstrated for the membrane hydrolysis and glucose transport. The immobilisation stress evoked different changes in the regulatory properties of enzymes. The data obtained suggest that stress reduces the stability of the enzyme transport control of the enterocytes' membrane through various regulatory mechanisms.
In anesthetised cats' m. gastrocnemius, under conditions of stabilised perfusion pressure, preservation of the sympathetic effect against the background of reactive and working hyperemia was shown in both rhythmic muscle contractions and in single tetani. The reactive hyperemia practically did not develop during sympathetic stimulation whereas the working one turned out to be a short-term one and considerably weakened as compared with the control.
In 21 alert rabbits staying for 1 hr in normoxic nitrogen-oxygen mixture under the pressure 6 kgs/cm2 and 1/2 hr respiration in air at atmospheric pressure, the increase in loading the respiratory system's muscles induced compensatory responses directed to preservation of the necessary level of lung ventilation. Total electrical activity enhances in the inspiratory muscles, and the pattern of separate motor units' discharges changes: firing rate increases, doubling and shift of discharges in the expiratory phase occur as well as alternation of activity in different motor units, recruiting of additional units, which seems to aid to the increase of the contraction force.
Stimulation of the supraoptic nucleus in surviving coronal sections of the hypothalamus elicited in the paraventricular nucleus the appearance of focal potentials reflecting the generation of action potentials of a population of cells. Repeat stimulation was accompanied by a decrease in the descending phase of the focal potentials. Tetanization of the supraoptic nucleus led to the appearance of an additional wave in the descending phase of the focal potentials which was maintained for 15 min. The data obtained attest to the functional plasticity of cells of the paraventricular nucleus of the hypothalamus.
Using a new, in vitro, experimental approach the transport of glucose, galactose, fructose and glycine in seroso-mucosal direction in the small intestine, was studied under different modes of oxygenation. In case of monosaccharides under the oxygenation from serosal surface, the substrate concentration is lower in the small intestine tissue than under anoxia. The effect of the oxygenation from serosal surface on the galactose transport was shown to be sensitive to absence of sodium ions, ouabain, phloretin, and not sensitive to phlorizin. The data obtained corroborate the hypothesis of the existence of a mechanism pumping off monosaccharides enterocytes through the basolateral membrane.
The activity of the small intestine's peptide hydrolases is higher in 1-day old rats than in adult rats, whereas levels of activity of alkaline phosphatase and diglycyl glycine peptidase do not differ significantly in these two groups of the rats. Our own data on carbohydrases corroborate other authors' evidence and reveals that activities of lactase, sucrase and maltase are either absent or very low in the first days of life and sharply increase by the third week of postnatal development. Adaptive changes of regulatory properties of lactase and alkaline phosphatase are revealed.
Resection of the proximal portion of small intestine impaired the inhibition of spontaneous gastric secretion induced by the hystodile H2-receptors blockade in rats. The data obtained suggests participation of enteral mechanisms in the inhibition of gastric secretion.
Effects of taurin, somatostatin, serotonin and noradrenaline upon the vagal chronotropic action and its components were studied in anesthetised cats. The data obtained suggests the existence of a specific transmitter link for vagal tonic and synchronizing effects upon cardiac rhythm.
Male Wistar rats were subjected to normoxic helium-oxygen mixture under 40 kg/cm2 pressure with subsequent decompression. Their brain's Ach, dopamine, glutamate, substance P were shown to change the turnover rate of the synaptosomal PPI. The findings suggest an unspecific mechanism of action of high tension helium on the neurons. The data obtained shows the high pressure neural syndrome not to be connected with metabolic change of a single neurotransmitter.
Hypoglycemia at the initial stage of the prenatal development decreased the level of glucose in the rat blood, increased glucose-6-phosphatase in the liver. Hyperglycemia increase the glucose content in the blood with relatively minor changes of the glucose-6-phosphatase activity and oxidation of hydrocarbonates.
After 3-hr cooling stress, the activity of the erythrocytes' Na,K-ATPase was decreased by 28.9 per cent in rats, its complete restoration occurring within 24 hours after the stress. Possible reasons and factors inducing a disorder in the enzyme activity under conditions of hypothermia, are discussed.
Noradrenergic and GABA-ergic systems were correlated and dominated in the processes of spinal cord segmentary apparatus superactivity compensation. An increase in c-GMP content in the spinal cord suggests an intensification of the activation mechanism. An increase in the c-AMP content may suggest an inhibition of the compensatory intensification of noradrenergic or GABA-ergic mechanisms.
Structural sex-depended differences were revealed in 7 out of 10 hypothalamic paraventricular nuclei under study in DB/DB C57 BL-K56 mice. Sex-dependent differences were also found in the responses to diabetes mellitus in 6 of these nuclei. The data obtained seem to corroborate the sex dependence of the paraventricular-vagal neuronal system involved in the control of carbohydrate homeostasis.
