[Ultrastructure of the rat gastric mucosal parietal cells in thiamine deficiency]

The effect of the thiamine deficient diet on the ultrastructure and secretory response of parietal cells of the rat gastric mucosa was studied. The control group consisting of fasting animals showed 60% of the parietal cells to be in a presecretory state. Subcutaneous administration of histamine to the control animals was accompanied by secretion of 512 +/- 128 mkekv H+ over 3 hours, with only 18% of the parietal cells remaining not involved in the secretory process. In thiamine-free diets the number of secreting cells in fasting animals amounted to 23%, rising to 35% after histamine administration. At the same time a three-fold decrease in the secretory response (170 +/- 21 mkekv H+ over 3 h) was observed. Thiamine deficiency in the diet is also accompanied by inhibition of the transketolase activity in the gastric mucosa homogenate, which varied from 0.706 +/- 0.032 mcmole (control animals) to 0.344 +/- 0.034 mcmole of sedoheptuloso-7-phsophate/h per 1 mg protein (test animals). Potentialities of the pentose cycle participation in secretion are discussed.