The cytochemical section-bioassay of gastrin-like activity

A cytochemical section-bioassay of gastrin-like activity is described in which such activity in plasma is assayed by its stimulation of carbonic anhydrase activity in serial, 18 micrometers-thick, sections of suitably prepared gastric fundus of the guinea-pig. The index of precision was 0.1 +/- 0.05 (mean +/- SEM; n=8). Fiducial limits were 75-134%. Intra-assay variation was +/- 6.4% (n=4); inter-assay variation was +/- 16.3% (n=3). The mean gastrin-like activity in the plasma of 15 fasting normal subjects was 5.1 +/- 0.49 x 10(-12)M (range 1.4-18.2 x 10(-12)M).