Acta physiologica Polonica最新文献

This study was designed to determine the rates of gastric emptying of water, saline and a 20% glucose solution in patients with gastric and duodenal ulcers. In all subjects, gastric emptying was fastest after administration of the saline, slower with water and the slowest with glucose. Significant statistical differences (p less than 0.05) in emptying rates between normal subjects and the group with duodenal ulcer were seen when water and saline but not glucose were used. We conclude that inhibitory effects of the osmotic receptors are not changed in gastric and duodenal ulcer patients. However, the emptying rates were higher when osmotic stimulus was withheld.

The effect of several concentrations of 7-0-hemisuccinyl, 7-deacetyl forskolin on ri was studied by means of microelectrode and single sucrose gap techniques. Twenty mumol.l-1 of forskolin added to the sucrose gap lowered ri by 15% below the control value. The drug applied at 50 mumol.l-1 initially decreased ri by 31%, and then it increased the resistance by 43% above the control value. The possible mechanisms underlying these effects are discussed in terms of cAMP and Ca action on the cell coupling.

Spreading of epileptiform activity in the central nervous system is one of the fundamental problems in epileptology. The patterns of spreading of after-discharges in the hippocampus and entorphinal cortex were studied in acute experiments and using the kindling model of epileptogenesis. Three methods were used to determine the time relations between EEG signals from different brain areas; visual inspections, average amount of mutual information (AAMI) and phase spectrum method. The analysis methods used are adequate for quantification of the degree of coupling between different EEG signals during an afterdischarge, but should be used jointly since different signal features are taken into consideration by different methods. During an afterdischarge only at the beginning the focal area is clearly leading the other brain areas; thereafter the pattern becomes more complex.

We tested the hypothesis that the reduction of automaticity during the embryonic development of chick ventricular myocytes is correlated with the number of sialic acid residues at the cell surface. The major findings were twofold. First, the sialic acid content of ventricular tissue fragments declined during the period between 4 and 17 days of development; however, when a 26% reduction of cell surface area was taken into account, the surface density of sialic acid at 7 and 17 days was not significantly different. Second, the sialic acid content of ventricular cell aggregates (after 3 days in gyratory culture) increased during the same two-week period. On the surface of these cells, the density was significantly greater at 17 days than at 7 days, even after a 17% increase in cell surface area had been taken into account. When the developmental increase in sialic acid content was compared with a concomitant decline in aggregate beat rates, we calculated a correlation coefficient of 0.85. Thus, while there could be some relationship between aggregate automaticity and sialic acid content, there appears to be no such correlation for fragments of chick ventricle.

The properties of 125I-apamin binding with rat central nervous system slices were analysed in vitro using computerized densitometric autoradiography. Scatchard analysis performed for the data of binding experiments in rat brain and spinal cord demonstrates that apamin binds to a single class of non-interacting binding sites in all investigated structures. The dissociation constant values (KD) were similar in all investigated structures (31-38 pM). The maximal binding capacity (Bmax) was observed in the structures of limbic olfactory system (30 fmol/mg protein), the lowest in brain white matter (0.5 fmol/mg protein). It is concluded that the observed pattern of 125I-apamin binding might represent the topography of a class of Ca2+ dependent K+ channels in the rat central nervous system.

Experiments have been done on conscious dogs (6 animals) to study vagal influences on small bowel motility. First group (3 dogs) was prepared with gastric and esophageal fistulas, the second group (3 dogs) with gastric fistulas. Both groups had monopolar silver electrodes placed along small bowel. Stimulation of vagus with sham feeding (SF) increased MMC period of about 21%. Insulin and 2DG infused intravenously increased MMC period at lower dose range and in high doses induced fed-like pattern of motility. Supradiaphragmatic vagotomy done in the second group animals does not change significantly fasted as well as fed motility pattern. These data suggest that central and peripheral vagal input is required for inhibition MMC activity and development fed motility pattern.

The temporal relations between simultaneously recorded neurons of the nucleus ventralis lateralis (VL) of cat thalamus were studied. The interaction and the functional connections between individual VL neurons are described. This was achieved with an application of cross correlation techniques. The response patterns of different individual neurons to somatic sensory and photic stimuli were also analyzed. For the purpose of classifying neurons as thalamocortical relay cells (T-C) and non relay cells (N-C) which do not project to the motor sensory cortex antidromic cortical stimulation was used. This stimulation was also used as conditioning one when proceeded peripheral stimuli. To analyze the nonspecific specific interactions upon single neurons conditioning photic stimuli were applied. The results show that T-C neurons are antidromically excited from a wide cortical areas and that the functional interaction between T-C neurons is mediated by a shared input from common sources. It is further postulated that N-C cells interposed between relay neurons subserve the functions of gating units modifying the neuronal network of lateral ventral nucleus of the thalamus.