Acid secretion and mucosal blood flow in the distal and proximal parts of the canine parietal cell mass in response to cholinergic stimulation.

Dogs provided with one denervated gastric pouch in the distal part of the corpus fundus and another of equal size in the proximal part were studied during stimulation with bethanechol chloride. Dose-response curves were determined for acid output and for mucosal blood flow, which was measured with the neutral red technique. ED50 for acid output was almost identical for the two pouches, giving a value of 1.13 (median) for the ratio of ED50 proximal pouch to ED50 distal pouch, which is between the ratios of 3.54 and 0.65 noted for pentagastrin and histamine, respectively in earlier investigations. The ED50 for blood flow was significantly lower than that for the simultaneous acid output, with a value of 0.28 for the ratio of ED50 blood flow to ED50 acid output, which gives an intermediate position between the ratios for pentagastrin (0.13 and 0.21 for the distal and proximal pouch, respectively) and histamine (0.61 and 0.73) obtained in earlier investigations. It could be hypothesized that the above differences in ratio between these three agonists reflect a difference at the receptor level of the parietal cells and the arterioles.