Physiologia Bohemoslovaca最新文献

The capability of cyclohexylphenol exaprolol of protecting the ischaemic myocardium during ischaemic cardiac arrest was assessed in the isolated working rat heart. Exaprolol added to the perfusion medium in a dose of 10(-7) mol.l-1 only minimally influenced the left ventricular function (reduced the stroke volume by 18.84% and cardiac output by 14.63%). The hearts were subjected to global ischaemia for 75 min at 26 degrees C and subsequently reperfused for 60 min at 37 degrees C. The recovery of left ventricular function following reperfusion, expressed as a percentage of preischaemic functional performance was used as an indicator of the ischaemic tolerance of the heart. The effect of exaprolol on sarcolemmal (Na+ + K+)-, Mg2+- and Ca2+-ATPase activities was also examined. Exaprolol-pretreated hearts revealed better postischaemic recovery of the left ventricular dP/dt max and stroke volume as well as improved efficiency in the transformation of chemical energy to mechanical work. Exaprolol in 10(-4) mol.l-1 concentration significantly stimulated the specific activity of sarcolemmal (Na+ + K+)-ATPase. Possible mechanisms of the salutary effect of exaprolol on the ischaemic heart are discussed.

Electrically evoked hippocampal afterdischarges are used as a model of partial epileptic seizures with a complex symptomatology and for testing anticonvulsants and toxic substances. Stimulating electrodes were implanted in the dorsal hippocampus of 16 laboratory rats and when the animals had recovered they were stimulated (15-s series, 8 Hz, pulse length 1 ms) with a voltage double the threshold value for a tissue response. The following features of the evoked afterdischarge were evaluated: the duration of the first phase of the afterdischarge, the duration of the non-active interphase, the duration of the second phase and the number of "wet dog shakes" (a constant accompaniment of hippocampal afterdischarges). Localization of the electrodes in the CA1 (n = 7) and CA3 (n = 7) region of the hippocampus made no difference to these parameters and in both cases the measured and evaluated data were the same. The afterdischarges were always accompanied by a marked orientation reaction. The study showed that when using macroelectrodes to stimulate the dorsal hippocampus, their localization in the CA1/CA3 is not of critical importance.

The authors describe the clinical and electroencephalographic findings in 220 children with focal and secondary generalized epilepsies without gross structural aetiology, with the aim of evaluating the significance of hemispheric motor prevalence for the formation, activity and possibility of compensation of the focus. Focal epileptogenesis was observed significantly more often: a) in partial seizures with elementary symptomatology in the motor non-dominant hemisphere, b) in the motor non-dominant hemisphere in boys, c) in the whole series, irrespective of the form of epilepsy and sex, in the motor nondominant hemisphere in children under the age of six and in the motor dominant hemisphere in children over the age of six. The findings in partial seizures with an elementary motor symptomatology probably arise from the very close relationship to motor areas of the cerebral cortex, in boys from evidently greater hemispheric functional asymmetry than in girls and the age correlation from unequal maturation of functionally identical parts of the brain hemispheres during ontogenesis.

The central effect of mescaline and of its derivative N-[3,4,5- trimethoxyphenylethyl]-aziridine (FAZ) after their stereotaxic administration into the lateral ventricle of the brain was studied in behavioural experiments on rats. The effect of the two substances was tested by a method studying memory elicitation in response to appetitive motivation in a multiple T-maze. The results show that both substances worsened the behaviour in question. The negative effect of mescaline (lengthening of the time of passage through the maze) was manifested both immediately and several weeks after a single dose. FAZ likewise worsened the test reaction, but its effect was less pronounced than that of mescaline.

A computer controlled equipment is described for computer analysis of isometric contractions of cardiac muscle by different modes of excitation. Both the method and the programme are presented. The following parameters are analysed: half and full contraction time, half relaxation time, maximum force developed during contraction, maximum rate of force development. The same computer is simultaneously used for controlling the stimulation.

A characteristic feature of the body temperature regulation of euthermic golden hamsters is a great individual variability of body temperature in the thermoneutral zone. Resting values of the total metabolic rate (M) at ambient temperature 30-34 degrees C vary from 5.3 to 8.8 W.kg-1 between individuals, body temperature reaching 33.5-37.7 degrees C (subcutaneous temperature, Ts) and 35.4-39.0 degrees C (hypothalamic temperature, Th). The dependence of metabolic heat production on steady deviations of peripheral and central body temperature from the resting values in nonlinear in general, but the unknown functional relationship delta M = f (delta Th, delta Ts) can be replaced by a single linear regression function of Ts by neglecting the change of central body temperature: delta M = 2.14-2.00. delta Ts. Total body thermosensitivity of the golden hamster determined from steady changes of rectal temperature and metabolic rate after external cooling is -6.8 +/- 1.3 W.kg-1. degrees C-1.

Various theories have been put forward to explain the regenerative capacity of liver tissue induce by partial hepatectomy (PH). One of them presumes the existence of humoral factors stimulating proliferation of the liver tissue. We evaluated the course of liver regeneration after 65-70% PH as influenced by dialysates (DIA) of the organs of a rat killed 17 h after PH. In addition to kidney DIA, we were particularly interested in the effect of liver and spleen DIA. The experiments were carried out on rats weighting 310-370 g. Kidney, liver or spleen dialysate was administered subcutaneously and the rats were killed 12 or 24 h later by exsanguination from the abdominal aorta. In further rats, PH was performed 24 h after administering DIA and the rat were killed 18, 24, 30, 48 and 72 h after the operation. The initiation of liver regeneration was stimulated by all the given DIA, but especially by liver DIA. The faster onset of liver regeneration 18 h after PH in rats given spleen DIA is interesting. DIA did not greatly affect the hepatocytes of intact liver, but accelerated the initiation of liver regeneration after PH by synchronizing the cell cycle of proliferating hepatocytes. DIA obtained 17 h after PH contained substances which primarily stimulated liver DNA synthesis. From the changes in inhibition of the migration of spleen macrophages in the medium containing liver antigens, and from the circulating immunocomplex values, we conclude that DIA activation of the immune system, a well as the hepatic stimulator substance contained in the DIA, participates in acceleration of the liver regeneration process.

The effect of chronic administration of phenobarbital (from the 4th to the 16th day of incubation) combined with chronic spinal decentralization (decapitation at stage 11-13) on the development of spontaneous motor activity (recorded on the 17th day of incubation) was studied in 4 to 17-day-old chick embryos. 1. Combination of the two experimental treatments led to summation of their negative effect on development; spontaneous motor activity fell to 15.2% of the control value (to 26.9% after the isolated administration of phenobarbital and to 30.5% after isolated decapitation). 2. Metrazol activation of motor activity (100 mg/kg egg weight) after combination of the two factors was relatively no different from the results after their isolated use. 3. The acute administration of GABA (100 mg/kg e.w.) likewise induced relatively the same depression of spontaneous motility as after isolated chronic decapitation and the isolated chronic administration of phenobarbital. The results confirm the hypothesis of the significance of spontaneous activity of the spinal motoneurones for their survival and their actual functional development during the embryonic period.

Diazepam, a drug with hydrophobic properties, was used as a model for studying its distribution (after intraduodenal administration) into the central lymph of rats. The intestinal lymph, which prevails in the central lymph, was modified for the presence of total lipids (chylomicrons) by means of fasting, a normal or an artificial diet (olive oil). The lymphatic levels of diazepam exceeded the corresponding blood levels in the fed and oil-fed group; the levels were steady in the fasted group with the exception of the absorption phase of the curves. The kinetic parameters assessed in the blood and lymph of the individual groups obtained by mathematical evaluation of the concentration curves differed because of quantitative differences in the presence of chylomicrons in the lymph. Lymphatic bioavailability in comparison with i.v. administration was found to be substantially lower.