Granular dissolution of mast cells and histamine release by compound 48/80 in the isolated guinea-pig heart.

It has been shown previously that guinea-pig tissues are highly resistant to the compound 48/80. Very high doses of 48/80 cause histamine release by a cytotoxic process. However, release of histamine from guinea-pig heart can be produced by concentrations of 48/80 as low as 20 micrograms/ml. In this case the mast cells show only morphological signs of matrix dissolution with no changes in the cell membrane or other intracellular organelles. These results are similar to those observed in in vitro anaphylaxis and are indicative of non-cytotoxic histamine release. Dibutyril cyclic adenosine 3', 5', monophosphate (db. cAMP) (10(-4)M) potentiated the granular matrix dissolution and histamine release produced by 48/80 in the isolated guinea-pig heart. The compound 48/80 did not release histamine in the pulmonary perfusate of guinea-pig lung even in a dose twice as much than that used in the heart.