[Changes in electrical potentials of gastric mucosa during various types of experimental hypoxia]

In experiments performed on anaesthetized male and female Wistar rats the effects of different types of hypoxia on the electrical potential difference (PD) between the inner and the outer sides of the gastric wall were examined. The PD was determined by mean of the Digital Multimeter VC-10T, Unitra, and the calomel electrodes connected with the KCl-agar bridges. There were four series of experiments carried out in which hypoxia was produced by: I--low atmospheric pressure (hypobaric hypoxia) corresponding with the altitudes of 2500, 5500, 8500 and 10,500 m above sea level, II--1 min. nitrogen breathing (anoxic anoxia), III--bleeding ca. 1% of the body weight (anemic hypoxia), IV--the gastric vessels ligation (ischemic hypoxia). There were also performed the adequate control experiments of each series. In all types of hypoxia (I--IV) a decrease in the PD was observed. The value and rate of this decrease were dependent on the type, grade, duration and rate of hypoxia. In the conditions of the hypobaric hypoxia simulated altitude 10,500 m only evoked the statistically significant PD drops, by 31%. The nitrogen breathing caused the PD decrease by 23% and the anemic hypoxia by 18%. In the ischemic hypoxia the total disappearance of the potential difference (PD = 0 mV) was observed. In the control experiments small non significant fluctuations, not exceeding 4%, occurred only. The decrease in the PD of the gastric wall observed during hypoxia could be explained by the changes in the membrane transport e.g. the back-diffusion of Na+, Cl-, and H+ ions.