Changes of regional gastric flow measured by hydrogen clearance techniques after histamine stimulation in conscious animals.

Gastric microcirculatory changes were studied by means of hydrogen clearance techniques in conscious cats during histamine stimulation. A considerable increase of corpus mucosa flow occurred, whereas a less substantial increase of antrum mucosa flow was observed during stimulation with histamine at 2 micrograms/kg/min, intravenously. Stepwise increase of infused histamine was accompanied by a gradual increase of corpus flow in the mucosa, which during supramaximal stimulation decreased slightly but still remained considerably elevated above control values. A similar decrease of antral mucosa flow occurred earlier during maximal stimulation, suggesting shunting of blood from the antrum to the corpus region. Total gastric flow measurements performed in anesthetized animals similarly showed decreased flow at a rate of histamine infusion which produced supramaximal stimulation in the conscious animals. However, total gastric flow remained elevated also during this stage compared with prestimulation values. A hypothesis of a dual effect of histamine on the gastric circulation is suggested, including regulation of flow through generalized vasodilatation and increased metabolic activity in the parietal cell mass.