EFFECT OF HISTAMINE ON SOLUBLE AND MEMBRANE-ASSOCIATED CARBONIC-ANHYDRASE (CA) ACTIVITY OF PIG AND BOVINE GASTRIC-MUCOSA

1. As part of their characterization, the effect of histamine (H) on b oth soluble and membrane-associated carbonic anhydrase (CA) activity o f pig and bovine gastric light microsomal membranes was investigated. 2. H did not affect the activity of soluble CA purified from pig oxynt ic mucosa, whereas 10(-7) and 10(-4) M H produced a significant enhanc ement of pig gastric firmly-membrane-associated CA activity at 20 and 30 degrees C (about 2-3-fold), but it failed at 0 degrees C. The incre ase of activity produced by H occurred within 1 min and it was maintai ned for at least 15 min. 3. H also stimulated bovine gastric firmly-me mbrane-associated CA activity, the stimulation also being dependent on temperature.