Physiologie (Bucarest)最新文献

This survey provides an outline of some recent integrative research of stress, concerning two main approaches: psychoneuroendocrinological and mathematical. The first is focused on the progress of the study of nontraditional stress hormones and on their nervous control, the second on the contribution of statistical computation of data and on the construction of various models of stress.

We studied the influence of cloprostenol (CIPG) 200 micrograms/Kg i.p. (a synthetic analogue of PGF2-alpha) and of imidazol 70 mg/Kg i.p. (a selective inhibitor of thromboxane synthetase) on fasting glycemia and on hypoglycemia induced by Actrapid insulin 0.5 UI/Kg i.p. to rats (male adults). The determinations of glycemia were made 60 minutes and 3 hours after the administration of the substances. The tests were made in groups of 20 animals which were not fed 14 hours before the experiment, but were not deprived of water. The results were interpreted statistically by means of the "t" test. The data obtained show that CIPG 200 micrograms/Kg i.p. is a significant hyperglycemic icosanoid (statistically p less than 0.01) both in the case of fasting glycemia and in the case of insulin hypoglycemia. The hyperglycemic effect was stronger at 60 min. Imidazol does not modify significantly either glycemia or insulin hypoglycemia, which pleads for a more reduced implication of thromboxanes in the regulation of glycemia in comparison to the prostaglandins.

Psychoneuroendocrine stress-induced syndromes were characterised as expression of the activity of neuroendocrine transducers. A physiopathologic classification delineated the diseases which appeared as a result of the increase of the endocrine response to acute stress, i.e., catecholamine cardiomyopathy, reactive hypercortisolism, amenorrhea, infertility, sexual dysfunction of euthyroid sick syndrome in man and immunosuppression. The clinical diseases secondary to chronic stress, together with their physiopathologic therapy, i.e., central hypocorticism and psychosocial dwarfism, are described. They are produced by active inhibition of the endocrine response mechanism called by us: dysprotection.

The eicosanoids are a system of lipid autacoids that are considered to play a role in the modulation of central nervous system (CNS) functions. This modulating effect seems to have three components: a) modulation of neuronal function and especially involvements in biological signal transduction at the level of the neuronal membrane: b) modulation of neurotransmitter release at synaptic level; c) modulation of the response amplitude of some CNS centers and areas to various stimuli, with implications in animal and human behaviour. Personal data show that cyclooxygenase inhibitors lower the seizure threshold and amplify the tonic aspect of the electric shock-induced seizure, while imidazole (thromboxane synthetase inhibitor) has no influence on the duration of seizures and seizure-free intervals, but makes the seizures have a clonic rather than tonic aspect.

Chronic and acute effects of L-Carnitina (vials of 1 g L-Carnitina endovenous; per orally administered vials of 1 g L-Carnitina; tablets of 1 g L-Carnitina) were recorded in 110 top athletes (rowing, kayak-canoe, swimming, weightlifting medium and long-distance runners), 47 girls and 63 boys, by six double blind placebo trials and cross over. Significant changes were registered after L-Carnitina treatment (both for a single dose or after 3 weeks of treatment) compared to placebo, for FFA, triglycenides, lactic acid after exercise, evoked muscular potential, plasma carnitine (free and acetyl-carnitine), urine carnitine (free carnitine) and others. The authors explain these changes by the increase of free carnitine, which permits a larger quantity of FFA to enter the mitochondria and to be more extensively used as energy source in endurance and strength efforts. Based on these results the authors recommend L-Carnitina as an ergogenic aid in elite athletes, especially in endurance and strength sports.

Bovine aortic endothelial cells in culture have been incubated with human low density lipoproteins (LDL) characterized in their cholesterol content. The incubation was done at different time intervals up to 72 h and various LDL concentrations. It began after endothelial cells had been starved for 24 h in lipoprotein deficient serum. The transfer of some LDL-components to endothelial cells plasmalemma was monitored by measurements of membrane fluidity. Namely, the fluorescent probe trimethylamonio-diphenyl hexatriene was inserted in the cell membrane and fluorescence anisotropy was determined; a higher fluorescence anisotropy means a higher rigidity of the plasmalemma. The results show that the rigidity of the endothelial cell plasmalemma increased progressively with the time of incubation (+11% to +19.5% after 24 h and 72 h, respectively for the concentration of 200 micrograms. LDL-cholesterol/dish) and with the greater amount of cholesterol in LDL (+10.9%) for 200 micrograms LDL-cholesterol/dish to +15% for 800 micrograms LDL-cholesterol/dish after 24 h incubation). In order to see if the LDL material transfer proceeded by receptor-mediated endocytosis of LDL and/or directly through aqueous solution a lysosomal inhibitor, chloroquine, was used at the concentration of 20 microM for preventing the lysosomal hydrolase activity. In the presence of this inhibitor the fluorescence anisotropy in treated endothelial cells increased by a lesser amount, suggesting an approx. 30% participation of intracellular route. Therefore, the transfer of material (probably cholesterol) from LDL to endothelial plasmalemma could take place both by receptor-mediated endocytosis and directly through the aqueous solution.