Effect of sub-diaphragmatic vagotomy on gastric mucosal mast cell population in pylorus ligated rats.

Gastric mucosal mast cell population was studied following sub-diaphragmatic vagotomy in albino rats, 6 and 12 h after pylorus ligation. Sub-diaphragmatic vagotomy significantly increased the gastric mucosal mast cell population in both 6 and 12 h groups, the increase being more in the latter. The results suggest that the vagal impulses act on the gastric mucosal mast cells causing their degranulation. Following vagotomy the contents stay bound within the mast cells. Increase in mast cell population with the longer experimental situation was possibly due to the continuation of normal turnover of the mast cells in the gastric mucosa. The present study, however, does not lead to a conclusion that the vagal influence on mast cell population is similar throughout the gastro-intestinal tract.     

Is acute surgical vagotomy an aggressor to gastric mucosa in pylorus ligated rats with and without indomethacin treatment?

Previously it was proved that intact vagal nerve is basically necessary for the development of gastric cytoprotection. The aims of this study were to receive further data about the role of vagal nerve in the development of gastric mucosal damage. The observations were carried out on Sprague-Dawley rats. Acute bilateral surgical vagotomy was done with pylorus ligation and/or indomethacin (IND) treatment (20 mg/kg, sc.) at the time of operation. The animals were sacrificed 4 h after the operation. The number, the severity (semiquantitative method), the mean size and summed surface (computer assisted quantitative method) of gastric mucosal damage, the H+ output and the mucosal PGE2 level were determined. It has been found that 1) the ASV itself (without IND or pylorus ligation) provoked gastric mucosal damage, which was more severe than in the pylorus ligated animals at 4 h; 2) IND was able to reduce the summed surface of mucosal damage after ASV; 3) ASV aggravated the gastric mucosal damage in pylorus ligated animals in spite of the decreased H+ output; 4) the PGE2 level was lower in vagotomized and vagotomized+pylorus ligated animals then in the control group, and the IND did not cause further decrease in its level after ASV. It has been concluded that the balance between aggressive and defensive factors of gastric mucosa was shifted to the aggressive side in surgically vagotomized animals.     

Ion transport in the heart atrial tissue of young and adult guinea-pigs and albino rats.

Rubidium shifts between the extracellular fluid and cells were studied in the isolated atria of guinea-pig and albino rat hearts. In the young of both species, rubidium transport from the incubation medium to the cells was much slower than in preparations from adult animals. That implies that the efficiency of membrane mechanisms for the transport of Na+ and K+ ions in the atrial tissue increases during postnatal life. This conclusion is further confirmed by the finding that the intracellular potassium concentration in the atrial tissue of the young of both species is lower, and the intracellular sodium concentration higher, than in adult animals. Conversely, the serum potassium concentration in the young is higher, and the serum sodium concentration lower, than in adult individuals.     

Plasma zinc levels in nephrectomized and ureteral ligated rats.

The effect of nephrectomy and ureteral ligation on the plasma zinc levels of zinc-supplemented and unsupplemented rats was studied. Bilateral nephrectomy, and to a greater extent bilateral ureteral ligation, resulted in a significant lowering of plasma zinc in the unsupplemented rats. Sham operation caused a lesser but significant lowering of plasma zinc which was not different from the effect of unilateral nephrectomy or unilateral ureteral ligation. Adding zinc to the drinking fluid of the bilateral nephrectomized rats raised their plasma zinc levels to that of sham-operated controls, but had no effect on the plasma zinc levels of the bilateral ureteral-ligated rats.     

Localization of histamine and histamine H2-receptor antagonists in the gastric mucosa.

Synopsis Histamine stimulates acid secretion by the parietal cell and this secretion is inhibited by the histamine H₂-receptor antagonists. Whole body autoradiography showed that radioactivity from¹⁴C-histamine was localized in the artery walls of the stomach and in the muscularis mucosae, but that the level in the fundic mucosa was the same as the blood.When the H₂-receptor antagonists burimamide, metiamide and cimetidine were labelled with³⁵S,¹⁴C or³H and dosed to rats, whole body autoradiography showed that the stomach was predominantly labelled in the glandular mucosa from 5 to 120 min after administration. Microautoradiography in the rat and dog after intravenous injection of [³H] metiamide or [³H] cimetidine demonstrated an uptake of tritium in the parietal cell cytoplasm that was 3- to 4-times greater than that found in adjacent peptic cells or areas of muscularis mucosa. The preferential labelling persisted at a low level up to 6 h after injection in the rat. The localization of radioactivity from the H₂-antagonists in the parietal cell cytoplasm correlates well with their pharmacological activity in preventing acid secretion from this cell.