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3H-leucine was injected intraperitoneally to hibernating and awakening sousliks and to those being conscious for one or two weeks. Water-soluble brain protein extracts were separated by disc electrophoresis to determine relative radioactivity of the most acidic fraction which, under similar conditions, corresponds to the nerve-specific protein S-100. It was shown that in the brain cortex and reticular formation, the incorporation of the acidic protein drastically increases on awakening and reaches the maximum value on the 7th day. The high level of 3H-leucine incorporation into the hippocampus of the hibernating animals does not substantially change during the egress from hibernation. This may be related to the fact that during hibernation the hippocampus retains electrical activity.

The water-soluble protein extracts from the different brain structures of hibernating animals were separated by means of disc-electrophoresis in polyacrylamide gel. The relative content of the most acidic protein corresponding to the nerve-specific protein S-100 under the same experimental conditions was determined in various physiological states. It is shown that the quantity of this protein in the brain stem increased in awakening animals as compared to the hibernating ones whereas its content in the cortex and hippocampus was stable.

Cerebral vascular responses (impedance method) and the regional cerebral blood flow (H2 clearance) in visual and sensomotor cortex during direct application of noradrenaline (NA) or stimulation of cervical sympathetic nerve were studied in chronic and acute experiments on monkeys and cats. NA in concentration 0.01 mcg/ml and pH--7.3 increased regional blood flow by 10 +/- 0.8%; NA concentration 0.1 mcg/ml had no effect on the flow, and NA concentration 1 and 2 mcg/ml decreased cortical blood flow by 9 +/- 1.2%, 21 +/- 3. Changes of pH from 7.3 to 6.9 decreased the constrictory effect of NA. Electrical stimulation of preganglionic nerves in chronic experiments decreased blood flow of the stimulated hemisphere by 19 +/- 1.4%, while only by 11 +/- 2% in acute experiments. The latency of vascular reactions of alert animals was very short, the reactions reaching their maximum within 15-20 sec. In acute experiments the maximum of the reaction decreased by 50% while the latency and duration increased. The data suggest that cortical vessels are sensitive to NA at the same concentrations as in normal physiological conditions and that vasoconstriction develops in response to sympathetic activation.

The microinjections of mock spinal fluid with various potassium concentrations into the cat and monkey brain tissue were made in acute and chronic experiments. The vascular reactions as studied with the microphotography and H-clearance method were found to be linearly related to the potassium concentrations within the range of 0--12 mEq/1, being constrictory below 5 mEq/1 and dilatory above that. An interaction between MSF potassium and pH seems to be weak if any, since the slope of the potassium vascular activity diagram remains unchanged within 6.8--7.8 pH change. The data obtained suggest that potassium ions take part in rCBF control since potassium is known to escape from stimulated nerve cells and thus substantially increase an extracellular potassium concentration.

rCBF under normal conditions in the rabbit, cat, and monkey brain was found to have a spontaneous periodicity while rCBF responses to afferent flicker stimulation usually revealed a double-phasic fluctuative pattern. This suggests that the rCBF regulatory system consists of not less than two regulatory chains with different time constants, and a feedback. The data on cerebral vascular responses to microapplication of mCSF solutions with various pH, potassium and catecholamines concentrations, suggest that rapid regulatory chains may be conditioned by potassium and neurogenic vascular effects, while slow ones could be mediated by CO2 and related pH changes.