Acta physiologica et pharmacologica Bulgarica最新文献

Oxidative modifications of blood serum in humans with and without coronary artery disease were investigated. Four parameters were analyzed: the intensity of serum fluorescence, which is indicative of the content of lipofuscine-like lipid peroxidation products; the content of thiobarbituric acid-reactive substances; the lag-phase of serum oxidation by azo-compounds; and the content of lipophilic natural antioxidants--alpha-tocopherol, beta-carotene and ubiquinol-9(10). It was found that coronary artery disease resulted in a significant increase of serum fluorescence and the content of TBARS. The atherogenic disorders in humans with coronary artery disease drastically decreased the lag-phase of serum oxidation in the presence of 2,2'-azo-bis-(2-amidinopropane) dihydrochloride. The oxidative modifications of serum were in close correlation with the balance of natural lipophilic antioxidants in blood serum, i.e. alpha-tocopherol, ubiquinols and beta-carotene. The contents of all antioxidants tested in serum were significantly decreased in patients with coronary artery disease.

The influence of androgens on the humoral immune reactivity development was investigated in male CBA mice. Positive correlation was found to exist between the plasma androgen level and the primary immune response throughout the pubertal period. The androgen-sensitive period of the humoral immune reactivity development coincided with the early stages of sexual maturation (from the 18th to the 30th day of life). In mice orchidectomized on the 18th day of life (18 ORx) the immune response followed the pattern of that in intact males up to 3 months of age but did not reach its peak at 4 months of age. On the contrary, in mice orchidectomized on the 30th day of life (30 ORx) the immune response was maximal at 2 months of age and remained high thereafter. Ten-day treatment of 18 ORx mice with daily injections of testosterone propionate at a dose of 0.1 or 1 mg/kg b.w. was ineffective in making their immune reactivity pattern similar to that in 30 ORx mice, while daily injections of 5 alpha-dihydrotestosterone (DHT, 1 mg/kg b.w.) was effective. The results suggest that the stimulating influence of testes on the humoral immune reactivity development in maturing mice is effected via DHT.

Ehrlich Ascites Tumor (EAT) cells, compared to liver, were less susceptible to peroxidation (measured by the TBARS method) induced by Fe2+/ascorbate, ADP/Fe2+ and H2O2/Fe2+/ascorbate. Higher thiobarbituric acid reagent products TBARS levels were found with Fe2+/ascorbate or after ultrasonication induced peroxidation in lipids obtained from Ehrlich cells compared to EAT cell homogenate with the same lipid content. This suggests that non-lipid and structurally membrane antioxidants factors are of less importance for induction by Fe2+/ascorbate than by ultrasonication. The resistance to induced lipid peroxidation (LPO) in EAT cells is associated with the lower level of lipids, the lower double-bond index, the lower level of fatty acids reacting with TBA, as well as with the relatively higher level of alpha-tocopherol per mg lipid in the EAT cells as compared to the liver.

The development and the characteristics of beta-adrenoceptor agonists-induced desensitization in rat trachea were studied. Tracheal strips were contracted with carbachol and cumulative concentration-response curves for various beta-adrenoceptor agonists were constructed before and after 30-min incubation either with the same beta-adrenoceptor agonist or with another beta-adrenoceptor agonist. Some problems of the in vitro desensitization in rat trachea were also considered.

Recent years have seen an increase in the information concerning the mechanisms of action of brain-gut neuropeptides (cholecystokinin (CCK), vasoactive intestinal peptide (VIP), somatostatin (SS)) on the biliary tract motility. This article is intended to extend our knowledge of the problem and based on our recent studies. Researchers and students interested in an historical overview of the subject, as well as in the information on the physiology and pharmacology of biliary smooth muscle are referred to earlier reviews (Ryan, 1981, 1987). The article focuses on the involvement of cholinergic mechanisms in the action of CCK, SOM and VIP on the gallbladder motility under in vivo and in vitro conditions. Some species differences in the responses of the gallbladder to CCK, VIP and ACh have also been described. Furthermore, new data about the interactions between CCK, SOM and VIP in the regulation of the gallbladder motility are presented.

Ten male Wistar rats were chronically implanted with conventional electrodes for sleep-waking stages detection. Three 12-hour electroencephalographic (EEG) registrations were performed once a week, after i.p. injection of the serotonin-2 (5-HT2) antagonist ritanserin at two doses (0.63 mg/kg and 2.5 mg/kg) and after ritanserin vehicle. The goal of the present study was to examine the effects of ritanserin on sleep-waking phases, and to obtain additional data about the participation of 5-HT2 receptors in the regulation of sleep and wake behaviour. Six sleep-waking stages were detected: active waking, quiet waking, light slow-wave sleep, deep slow-wave sleep, intermediate stage of sleep and paradoxical sleep. Each of the 12-h postdrug EEG records was divided into 3 consecutive 4-hour periods and the sleep-waking stages were scored visually for every minute of the whole postdrug period. The three periods were compared in order to evaluate the effect of ritanserin in dynamics. The results obtained showed a significant decrease in wakefulness and paradoxical sleep, a significant increase in slow-wave sleep (mainly the deep slow-wave sleep) and in the intermediate stage of sleep. These changes in the sleep-waking phases occurred in a dose-dependent manner, the larger the dose of ritanserin, the stronger the effect of ritanserin. The changes were more pronounced during the first 4-h period and then a restoration in the sleep-waking phases took place except for the paradoxical sleep.

The effects of the Ca2+ and 5-HT1 and 5-HT2 receptor antagonist dotarizine and of some other agonists and antagonists of different 5-HT receptor subtypes administered alone or in combination with the 5-HT uptake inhibitor fluoxetine (FLU) on nociception were studied, using a foot-pressure method (analgesy-meter testing). Dotarizine (DOT) administered at a dose of 50 mg/kg for 3 days orally significantly increased the pain threshold. Fluoxetine (FLU) administered at a dose of 10 mg/kg for 3 days also significantly increased the pain threshold. The combination of DOT and FLU abolished the analgesic effects of the two drugs. The 5-HT1A and 5-HT1B/1C receptor agonists buspirone and m-CPP decreased the pain threshold. The antagonists of 5-HT1A(NAN-190),5-HT1/5-HT2(methysergide), 5-HT2 (ritanserin), and 5-HT3 (ondansetron) receptors as well as the agonists of 5-HT2(DOI) and 5-HT3 (mCPBG) receptors increased the pain threshold. Fluoxetine at a single dose of 10 mg/kg differently influenced the effects of the 5-HT agonists and antagonists on nociception. Comparison of the effects of dotarizine with the effects of some of the agonists and antagonists of 5-HT receptor subtypes on the nociceptive and other actions suggests the possibility of a therapeutic value of dotarizine as an antimigraine drug.

A non-invasive method for recording the electrical activity of the gastric muscle wall is presented. Electrogastrograms (EGG) with cutaneous electrodes on the abdominal wall were recorded using an original electrogastrograph. High-quality records without cardiac artifacts allowed for identification of waves belonging to the quiescent or activity period of the migrating myoelectric complex (MMC). The amplitude of the waves of the activity period of MMC were almost twice higher than that of the waves of the quiescent period. The wave amplitude immediately after feeding increased two times and a half compared to that during fasting. The high-amplitude waves in the activity periods of MMC and after feeding in the electrogastromyograms (EGMG) of dogs corresponded to bursts of spike potentials with slow potentials, i.e. to intense gastric muscle wall contractions. The method could contribute to the diagnosis of gastric motility disturbances in clinical practice.

Acute blood volume expansion (AVE) is a potent stimulus for atrial natriuretic peptide (ANP) release. Since several central nervous structures are well known for their involvement in the regulation of fluid and electrolyte homeostasis and in the secretion of central ANP, we carried our experiments on 33 conscious Wistar rats in order to determine if the integrity of the supramammillary (SMA) hypothalamic area is essential for the peripheral ANP response to AVE. We performed stereotaxic electrolytic lesions of SMA in part of the animals. To obtain AVE we administered 2 mL saline/100 g b.m. for 2 minutes into v. jugularis through the chronically implanted venous catheters. Plasma ANP was assayed radioimmunologically. AVE significantly increased plasma ANP both in the intact animals and in the lesioned rats. This concluded that SMA is not involved in the regulation of peripheral ANP release during AVE.