Plasma histamine in pig: effect of food and pentagastrin.

Histamine may have a role in the physiological control of gastric acid secretion. We aimed to detect histamine release into the circulation during food and pentagastrin. Non-parametric statistical analysis was used. Seven pigs bearing iliac artery, iliac vein and portal vein cannulae were given a standard meal. Blood samples were collected at 10-minutes intervals over a period of 2 hours for histamine assay. There were no significant changes in whole blood and plasma histamine concentrations in the iliac arterial or venous blood. In portal venous blood, no significant changes were observed in whole blood histamine, but there were significant increases in plasma histamine 40 minutes after food (basal median: 149.0; range: 50.3-258.6 pmol ml-1; 40 minutes, median 214.9; range: 64.2-319.6 pmol ml-1). Four pigs were given pentagastrin, 6 micrograms kg-1 h-1 i.v. Iliac and portal venous bloods were collected for histamine assay before and 15 minutes after pentagastrin infusion. There were no significant changes in the whole blood histamine concentration in either iliac or portal venous blood. A small increase, mean 5%, of plasma histamine concentration was detected in the iliac venous blood (basal mean 242.9 +/- 21.7 pmol ml-1; stimulated mean 256.9 +/- 39.1 pmol ml-1). A 20% increase in the portal plasma histamine concentration was observed after pentagastrin (basal mean 240.1 +/- 13.2; stimulated mean 288.4 +/- 18.8 pmol ml-1). Both food and pentagastrin increase plasma histamine concentration in the portal vein. Pentagastrin has a greater effect than food.