Acta physiologica et pharmacologica Bulgarica最新文献

The effect of oral administration of vanadate (100, 200 and 400 nM for 30 days) on the activity of the detoxifying enzyme system glutathione S-transferase (GST) in rat liver and in several extrahepatic tissues was examined. Vanadate showed a high activity as GST inducer in liver and in small intestine mucosa followed by large intestine mucosa and kidney in a dose-dependent manner. No significant alterations in GST activity were observed in forestomach and lung tissues after vanadate. Vanadate treatment that resulted in an enhancement of GST activity impaired neither hepatic nor renal function as evidenced by serum glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, sorbitol dehydrogenase, urea, and creatinine. Since the ability to induce an increase of detoxifying enzyme activity by anticarcinogenic agents was found to correlate with their activity in the inhibition of tumorigenesis, the trace element vanadium might be considered a potential cancer chemopreventive agent.

The effect of neonatal 6-hydroxydopamine (6-OHDA) treatment on learning and retention and on the level of biogenic monoamines in some brain structures as well as the influence of the nootropic drugs--piracetam, aniracetam, meclofenoxate and fipexide on the 6-OHDA-induced effect was studied. Two- way active avoidance (shuttle box) was used. The levels of noradrenaline (NA), dopamine (DA) and serotonin (5-HT) in the frontal cortex, striatum, hypothalamus, hippocampus and pons were measured. In mature rats, injected with 6-OHDA (100 mg/kg s.c.) in the first 3 postnatal days learning and retention were impaired and the NA level in the frontal cortex and hippocampus was decreased. Piracetam (600 mg/kg), aniracetam (50 mg/kg), meclofenoxate (100 mg/kg) and fipexide (10 mg/kg) administered orally 5 days before and 5 days during training, abolished the amnestic effect of 6-OHDA and restored to control values the NA level in the frontal cortex and hippocampus. This finding suggests the important role of the noradrenergic neurotransmitter system in the 6-OHDA-induced amnesia, as well as in the favorable effect of the nootropic drugs tested on 6-OHDA-impaired memory processes.

The influence of the azacrown ether derivative benzylaza-15-crown-5 on myocardial tolerance to ischemia and on the functional state of the zone of myocardial ischemia during coronary artery occlusion was investigated in experiments on anaesthetized open-chest cats. The compound tested produced a dose-dependent antiischemic effect and prevented the development of myocardial ischemia. In experiments on isolated guinea-pig papillary muscle benzylaza-15-crown-5 inhibited the first and second components of the isoproterenol-induced muscle contraction. The compound decreased the maximal contraction force and had no effect on the cardiac cycle duration and on the time necessary for reaching maximal tension. It is suggested that the protective effect of benzylaza-15-crown-5 during myocardial ischemia is mediated through the inhibition of calcium release from the sarcoplasmic reticulum.

The aim of the investigation was to study the direct influence of T-actemodulin (TAM) on the Herpes Simplex Virus (HSV) infection in vitro and in vivo. HSV-1 (strain Vic) and HSV-2 (strain Nissa) were used in the experiments in vitro. The experiments were performed using multicycle and singlecycle growth tests. Seventy-five patients suffering from HSV infections (labialis and genitalis) were locally treated by 0.04% TAM-containing hydrophilic gel or water-washable cream (applied every 3 h). The results showed that TAM: decreased the infectious virus titre; reduced the infectious virus yield at the end of the single cycle of the virus replication; prolonged the latent period; and exerted an irreversible inhibitory effect on the infectious virus titre when applied at immediate early intervals after the infection. No relapses were observed in 84% of the patients treated with TAM. Eight percent of the patients were with only reduced relapses and in 8% of the patients TAM had a mild effect. TAM exerted a preventive effect against the disease when the treatment was initiated in the period of paresthesia.

Movements of the upper limb are well known to be preceded by electromyographic activity in leg and trunk muscles known as postural preadjustment. Brain potentials preceding the actual commencement of voluntary displacement were also described. The relationship between the occurrence of these two electrophysiological phenomena was investigated by performing two types of movement in three different body positions. Healthy subjects were free standing, sitting and standing with backsupport. When fast forward arm elevation was executed, the preceding Bereitschaftspotential was higher in amplitude at 500 msec before EMG onset and alongside midline scalp leads during sitting. The amplitude at 150 msec, immediately preceding movement, did not show significant differences related to body positions and there was no contralateral dominance. When index finger flexion was performed, it did not yield differences in the Bereitschaftspotential between sitting and standing positions. These findings suggest the existence of two separate stages of the preparatory process and an influence of the muscle mass involved in the stance perturbation during voluntary movement.

3H-flunitrazepam binding was studied in membranes from different brain regions and from kidneys and adrenals of young (5-month old) and aged (22-month old) rats. Decreased benzodiazepine receptor density (by 33.7%) was observed only in the cerebellum of aged rats. The number of benzodiazepine receptors was significantly increased in the hypothalamus (by 44.1%). Specific 3H-flunitrazepam binding was also significantly increased in both kidney and adrenal membranes from old rats.

The behavioral effects of extracts from ginseng stem and leaves (GL), standardized with respect to the total saponines, and from ginseng roots (G115), standardized with respect to the content of ginsenosides were examined in experiments on rats with undisturbed memory and in rats with experimentally-impaired memory (electroconvulsive shock) using the methods for active avoidance (shuttle-box) and passive avoidance (step-down, step-through), the water-maze method and the method for studying exploratory behavior. On multiple administration G115 exerted favorable effects on learning and memory and on the higher nervous activity as a whole. These effects greatly varied with the dose and administration schedules, with the rat strain, with the rat's ability to perform adequately in any particular learning task, and with the behavioral method. The extract from the overground part of ginseng (GL) had, in the majority of cases, an effect weaker than that of G115 or was without effect at all. Based on previous and present results, we discuss the role of the changes in brain biogenic monoamines induced by the extracts for their mechanism of action.

The conduction velocity of the impulses along the muscle fibers is one of the parameters of the extraterritorial potentials of the motor units allowing for the evaluation of the functional state of the muscles. There are no data about the conduction velocities of antigravity muscleaction potentials. In this paper we offer a method for measuring conduction velocity of potentials of single MUs and the averaged potentials of the interference electromiogram (IEMG) lead-off by surface electrodes from mm. sternocleidomastoideus, trapezius, deltoideus (caput laterale) and vastus medialis. The measured mean values of the conduction velocity of antigravity muscles potentials can be used for testing the functional state of the muscles.

The effects of different concentrations of 4-aminopyridine (4-AP) and tetraethylammonium (TEA) on the intra- and extracellular action potentials (ICAPs, ECAPs) of unmyelinated axons of Lumbricus terrestris were studied. The results showed different sensitivity of the axons to both potassium current blockers (4-AP and TEA), added to the medium. 4-AP led to spontaneous and single stimulus- evoked repetitive activity, manifested as a slow "burst" action potential propagation like "plateau" ICAP with oscillations. The ICAP duration of the TEA-treated axons increased mainly at the expense of the repolarization phase which reflected the increased duration of the ECAP recorded at long radial distances. The amplitude of the ICAPs after treatment with both blockers was decreased to 20% as compared to the controls (untreated axons) and ECAPs decreased to 40% in the TEA-treated axons. The conduction velocity (CV) of the action potentials was not significantly changed. The calculated total ionic current during the action potential upon TEA treatment was decreased and the duration of the outward phase was prolonged.