[The variability characteristics of the arterial pressure in man and animals]. / Osobennosti variabel'nosti arterial'nogo davleniia cheloveka i zhivotnykh.

The development of computer monitoring methods over haemodynamic parameters has made possible on objective quantitative estimation of blood pressure (BP) variability in humans and animals which can have both periodic and aperiodic feachers. The spectral analysis of spontaneous BP fluctuations reveals presence of several power peaks main of which, as well as in heart rate variability, reflect sympathetic and parasympathetic activity. Both in hypertensive patients and animal models of arterial hyper tension BP variability is higher, but its relationship with BP level is not realized in a simple causal scheme. Observations in prehypertensive period demonstrate an opportunity of dissociation between rates of BP level and variability increase. The pharmacological analysis permisses to suggest the sympathetic activation as the main cause of BP destabilization. Despite a leading role of baroreceptor reflex (BR) in damping of evoked BP fluctuations, its role in regulation of spontaneous variability seems to be ambiguous. The studies excluding episodes of locomotor and other activities from the curve analysis do not confirm a correlation between BP variability and BR gain. The spectral analysis of BP lability in animals with denervated mechanoreceptor zones has revealed BR effective control only of a low and superlow frequency areas (less than 0.07 Hz). The study of the regional blood flows in sinoartic denervated rats has concluded that the increase of their autonomy is the main reason of BP lability. The offset of BR efferent limb by ganglionic blocking agents or desympathization leads to analogical BP lability. Thus, BP variability seems to be a reflection of functional efficiency of BP stabilization mechanisms. Considering that on its origin, connections with other haemodynamic parameters, amplitude and frequency characteristics is a complex phenomenon, no one of mechanisms is an universal instrument of its regulation.

[The variability of the arterial pressure in waking normotensive rats]. / Variabel'nist' arterial'nogo davleniia u bodrstvuiushchikh normotenzivnykh krys.

Specifics of arterial pressure, interrelationships among the arterial pressure, heart rate and baroreceptor reflex, were studied in alert normotensive rats. Absence of any correlation between the middle level of arterial pressure and the latter's variability, was shown. No connections among the above parameters were found either.

[Effect of strophanthin and digoxin on the activity of succinate and lactate dehydrogenases and membrane Na+, K+-ATPase in the heart of rats with experimental myocarditis]. / Vliianie strofantina i digoksina na aktivnost' suktsinat-laktatdegidrogenaz i membrannoi Na+, K+-ATFazy v serdtse krys s éksperimental'nym miokarditom.

In rats with adrenaline-induced myocarditis conditionally therapeutic doses of strophanthin (2.7 mg/kg) and digoxin (0.89 mg/kg) were chosen according to performance of the test of swimming until the complete fatigue. The influence of drugs in these doses on enzymatic activity was evaluated by histochemical methods in heart of control and myocarditis rats. It was found out that both of cardiac glycosides decreased lactate dehydrogenase and membrane Na+, K+-ATPase activity and increased succinate dehydrogenase activity in rats with experimental myocarditis.

[Character of the baroreceptor reflexes in experimental arterial hypertension]. / Kharakter baroretseptornykh refleksov pri éksperimental'noi arterial'noi gipertenzii.

In normotensive, barodenervated rats and those with experimental renal hypertension, arterial BP, heart rate and behaviour were recorded during aversive emotional stress. Cardiochronotropic component of the baroreceptor reflex and the activity of the energy metabolism enzymes were tested in structures of the medulla oblongata. The depression of the baroreceptor reflex in hypertensive rats was accompanied by no significant changes of enzymatic activity in the nucleus tractus solitarii but led to biphasic reactions of the BP during emotional stress. A possible role of the baroreceptor reflex suppression in genesis of hypertension is discussed.

[Functional activity of the structures of the medulla oblongata in rats with arterial hypertension of renal origin (histoenzymological research)]. / Funktsional'naia aktivnost' struktur prodolgovatogo mozga krys pri arterial'noi gipertenzii pochechnogo geneza (gistoénzimologicheskoe issledovanie).

A quantitative histochemical study of succinate dehydrogenase (SDH) and NADH-dehydrogenase (NADH-D) activity in medulla oblongata structures was accomplished in rats with arterial renovascular hypertension of the "2 kidneys-2 clips" type lasting 5 months. The systolic arterial blood pressure measured by the tail-cuff method was 179 +/- 4 mm Hg in hypertensive rats versus 108 +/- 3 mm Hg in control. There was a significant elevation of SDH activity in the ventral reticular and commissural nuclei, while in the neurons of the vagus dorsal and ambiguous nuclei it was lowered. NADH-D activity was significantly increased in the neuropil of the hypoglossal nerve nucleus and reduced in its neurons. The general trend was also revealed toward reduction of the maximal and elevation of the minimal activities in other nuclei. These metabolic alterations reflect changes in the functional activity of vasomotor and other structures of the medulla oblongata in renovascular hypertension.

[Effect of emotional-pain stress on the activity of the gamma-aminobutyric acid system]. / Vliianie émotsional'no-bolevogo stressa na aktivnost' sistemy gamma-aminomaslianoi kisloty.

In experiments on rats the emotional-pain stress is studied for its effect on the activity of the gamma-aminobutyric acid (GABA) system in the forebrain and stem structures, on GABA catabolism and GABA metabolism-related energy metabolism indices in the hippocamp and frontal cortex neurons. It is shown that the stress effect is accompanied by the GABA level increase and GABA-transaminase inhibition with a simultaneous rise of the succinate dehydrogenase and glutamate dehydrogenase activity. The pain factor is established to be very important for changes in the activity of GABA-transaminase and succinate dehydrogenase. The found shifts in the GABA activity system are significant for neuromediatory and energy adaptation to the stress.

[Changes in the GABA-transaminase activity in various structures of the rat brain after administration of benzodiazepine tranquilizers]. / Izmenenie aktivnosti GAMK-transaminazy v razlichnykh strukturakh mozga krys pod vliianiem trankvilizatorov benzodiazepinovogo riada.

Quantitative histochemistry was used to study the effects of phenazepam, medazepam, diazepam, and nitrazepam on GABA-transaminase activity in different rat brain structures. Phenazepam and diazepam, which produced anxiolytic effect in low doses, selectively inhibited GABA-transaminase of the hippocamp. The degree of GABA-transaminase inhibition corresponded with pharmacological activity of the test benzodiazepines. It is assumed that inhibition of brain GABA-transaminase by benzodiazepines is linked with their interaction with GABA-benzodiazepine receptor complex.

[Quantitative histochemical study of the effect of benzodiazepine tranquilizers on cerebral GABA-transaminase activity]. / Kolichestvennoe gistokhimicheskoe izuchenie vliianiia benzodiazepinovykh trankvilizatorov na aktivnost' GAMK-transaminazy mozga krys.

The effect of diazepam and nitrazepam (0.5, 1, 2.5, and 5 mg/kg) on GABA-transaminase activity in the rat cerebellar cortex and hippocampus was investigated by quantitative histochemistry. Both the drugs suppressed the enzyme activity in the hippocampus; the maximal effect was produced by diazepam. It is suggested that the observed alterations are caused by the enzyme inhibition and also by a decrease of GABA turnover rate.

[Cytospectrophotometric study of GABA-transaminase in the rat cerebellar cortex]. / Tsitospektrofotometricheskoe issledovanie GAMK-transaminazy v kore mozzhechka krys.

Modification of the histochemical method for detection of GABA-transaminase activity is suggested. Optimal concentrations of the substrates and cofactors are chosen on the basis of kinetic study of the enzymatic reaction in the cryostat sections of the rat cerebellar cortex by the quantitative microspectrophotometric method. The method is intended for the quantitative histochemical analysis of GABA-transaminase activity in the brain sections.