Rat gastric histamine release: a sensitive gastrin bioassay.

Acid secretion and histamine release from the totally isolated vascularly perfused rat stomach are sensitive parameters for the biological effects of gastrin. By optimalizing the Ca2+ concentration of the vascular perfusate the sensitivity for stimulation of acid secretion was improved from 65 to 16 pmol/l gastrin 1-17 (G-17). Measurement of venous histamine before and after gastrin in each stomach preparation excluded inter-stomach variability and improved the sensitivity to 2 pmol/l G-17. This is the most sensitive gastrin bioassay reported, with a detection limit comparable to that of radioimmunoassay.