Cyclic AMP Content and Histamine Release in Rat Mast Cells

The relationship between the content of cyclic AMP (cAMP) in rat mast cells in vitro and release of histamine was studied with compound 48/80 and a variety of hormones and drugs that affect cAMP in tissues. Papaverine (0.1 mM) increased cAMP in mast cells 3-fold. No increases in cAMP were observed in response to other drugs unless papaverine was in the medium. Isoproterenol, epinephrine, prostaglandins E1, E2, or F2α produced further increases of cAMP in the presence of papaverine. Norepinephrine only slightly increased cAMP. Angiotensin II, vasopressin, bradykinin, and glucagon did not increase cAMP even when the drugs were used in concentrations as high as 0.1 mM. Compound 48/80 did not affect cAMP content in mast cells. Release of histamine induced by 48/80 was partially inhibited by PGE2, PGF2α, vasopressin, and angiotensin II in the presence of papaverine and by angiotensin II alone. Neither papaverine alone nor the combination of PGE1 with papaverine inhibited release of histamine. These data suggest, therefore, that changes in cAMP in rat mast cells are not correlated with inhibition of 48/80-induced release of histamine.