Acta physiologica Polonica最新文献

Examination of influence of divalent cations (Co2+, Ni2+, Mn2+) and organic blockers (verapamil and D600) on calcium efflux from resting mammalian myocardium shows that they either inhibit or increase transiently 45Ca2+ efflux, depending on the site of action. It seems that those agents whose sites of action are limited to the sarcolemma inhibit Ca2+ efflux. Co2+, Ni2+, verapamil and D600 belong to this group. Mn2+ ions which act also apparently on intracellular structures increase transiently Ca2+ efflux. Such a finding illustrates a diversity in mechanisms of action in a group of agents generally classified as calcium channel blockers.

Several observations indicate that the mylohyoid nerve (NV) may play a crucial part in the mechanisms of obstructive sleep apnea (OSA). The activity of this nerve normally counteracts the collapse of the upper airways during inspiration. Any reduction in this activity may thus facilitate the occurrence of apnoeic spells. We have studied the effects of ethanol and lung inflations on the activity of NV recorded along with the activities of phrenic and facial nerve in rabbits anaesthetised with chloralose-urethan, paralyzed with curare and artificially ventilated. Under the control conditions the NV exhibited phasic expiratory activity; after vagotomy and additional, inspiratory component was observed. Lung inflation strongly enhanced the expiratory activity of NV whereas both the phrenic and facial nerve activities (both phasic-inspiratory) were typically inhibited. An injection of 5 ml of 20% ethanol very strongly inhibited the NV activity. The results may confirm the importance of NV in the mechanism of OSA. The well-known fact that OSA patients are particularly sensitive to alcohol finds support in the response of NV activity to ethanol injection. The analysis of the patterns of discharges of the three outputs from the respiratory controller may additionally suggest that the Vth nerve nucleus is involved in the control of respiratory pattern.

Gastric emptying of a radiolabelled solid meal was studied in 19 women. The gastric emptying curves were analyzed with the use of a power-exponential fitting, and the results were related to the phases of the menstrual cycle. No significant differences between the phases of the menstrual cycle were found when the rates of gastric emptying were compared. However, different emptying patterns in each phase of menstrual cycle were revealed by the analysis of the curve shape parameter, S. The physiological and clinical relevance of the findings is discussed.

Angiotensin II (1 microgram) dissolved in water and given intracerebroventricularly on day 1, 15 min before the first learning session, enhanced rate of learning of active avoidance in rats over the next 7 days. However, the peptide, dissolved in 0.25 M NaCl, and given at the same dose and route, stimulated learning significantly more than that dissolved in water. A possible involvement of Na+ ions in facilitating learning action of A II is discussed.

The present study is a continuation of our previous experiments on DSIP activity which have revealed that nonapeptide DSIP inhibits hippocampal electrical activity of the 4-7 c/s frequency band. The aim of the present study was to find which of the known DSIP fragments is responsible for its activity, i.e. to find the active site of the molecule. The experiments were carried out with the entire DSIP molecule and its three different fragments. The method of threshold continuous arousal pattern (TCAP) monitoring was used as the indicator of DSIP activity. It was found that the entire DSIP molecule increased TCAP, while its 1-5 fragment decreased it 1-4 and 5-9 fragments had no noticeable effect.

The method of whey extraction in order to determine insulin concentration in colostrum and milk was worked out, checked and applied. The observation of insulin changes showed high and similar insulin concentration in whey samples of women, cows and sows colostrum on the day before and in the day of parturition. One day after delivery hormone concentration maintained high in case of women and sows but in cow colostrum it decreased to 1/12 comparing to the level on the parturition day. During the postpartum following days it was decreasing gradually in the colostrum of all three examined species; the process was very fast in cows, slower in women and the slowest in sows.

Under tolerance, evoked by multiple doses of pethidine (PD), the serum and brain tissue content of PD was related to diminished analgesic activity. Even though in tolerant rats no enhancement of PD biotransformation in the liver could be recognized (as followed by the measurement of hepatic esterase and N-demethylase activity), the amounts of both PD and nor-PD excreted in urine were increased under tolerance. The authors conclude that the faster disposition of PD may contribute to the development of tolerance.

The aim of this study was to determine the changes of the basic parameters of the erythrocyte system and the activity of some red blood cell (RBC) enzymes prior to and after a single physical effort leading to exhaustion. The study was carried out on male Wistar rats subjected to running on an electric rotating drum at a speed of 25 m/min. A single exercise caused a decrease in the RBC count, haemoglobin concentration (Hb) and haematocrit (Hct) by 21.9, 16.7 and 16.1%, respectively, and an increase in the reticulocyte count (Ret) by 661.5%. The exercise triggered also changes in the activities of some erythrocytic enzymes: pyruvate kinase (PK) activity increased by 12.4%, glucose-6-phosphate dehydrogenase (G6PD) by 37.8%, glutathione reductase (GR) by 30.8% and acetylcholinesterase (AChE) by 248.7%. These increases in the activities of RBC enzymes can be explained by an increase in the red cells turn-over.

In normotensive rats the effect of different doses of propranolol (1.0, 5.0 and 10.0 mg/kg i.p.) and ketanserin (10.0 mg/kg p.o.) on mean blood pressure and heart rate and on cardiovascular response to noradrenaline (0.1, 0.3, 0.5, 0.7 and 1.0 micrograms/kg i.v.) was examined. The drugs were given separately or together. Propranolol slightly reduced the hypotensive effect of ketanserin. On the other hand a decrease in heart rate caused by propranolol was not affected by ketanserin. Our results show that propranolol given with ketanserin did not change the effect of the latter on the cardiovascular system.

A possible improvement of +Gz acceleration tolerance, obtained in human subjects through administering specific volumes of water, viz. 7, 14 and 21 ml/kg body weight, to be drunk immediately before centrifuge examination in order to increase the volume of plasma, thus increasing the circulating blood volume, was the starting-point for this work. Two hundred healthy male subjects, aged 19.9 +/- 0.9, were classified in 4 main groups and 2 supplementary groups for examination. It was found that the water intake in volumes of 14 ml/kg body weight produced a significant mean increase in the acceleration tolerance of 0.8 G, and that of 21 ml/kg body weight improved acceleration tolerance by 1.1 G on the average. The increase tolerance to acceleration was maintained throughout a period of about 30 minutes (for 14 ml/kg body weight) up to approximately 50 minutes (for 21 ml/kg body weight). The favourable effect of water load in the body systems upon +Gz acceleration tolerance was probably due to the increase of plasma volume (by 5.24% and 6.98% for 14 and 21 ml/kg body weight, respectively).