Essential Role of ATP and Possibility of Activation of Protein Kinase C in Ca2+-Dependent Histamine Release from Permeabilized Rat Peritoneal Mast Cells

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Abstract
To elucidate the role of ATP in histamine release, the present study was performed using β-escin-permeabilized rat peritoneal mast cells. Ca2+-induced histamine release from permeabilized cells is totally dependent upon exogenous ATP in the medium. In the presence of Ca2+, ATP caused histamine release concentration-dependently at concentrations ranging from 0.01 to 5 mmol/l. The maximum release was achieved at 3 mmol/l of ATP in the medium. When the other adenosine nucleotides (AMP, ADP), or nonhydrolyzable ATP analogues (adenylylimidodiphosphate, βγ-methylene ATP) were added in place to ATP, no histamine release took place. Other ribonucleoside triphosphates (GTP, ITP, UTP and CTP) had little effect at the same concentration range. When the ribunucleoside triphosphate content of mast cells was determined by means of HPLC, ITP and CTP were not detectable. A millimolar range of the ATP content was determined in mast cells, but the amounts of other ribonucleoside triphosphates (GTP and UTP) were remarkably lower than that of ATP. These results seem to indicate that the ATP molecule plays a crucial role in histamine release from rat mast cells in association with its concurrent hydrolysis. Furthermore, 12-O-tetradecanoylphorbol-13-acetate and 1-oleoyl-2-acetylglycerol enhanced histamine release elicited in the presence of Ca2+ (0.1 μmol/l) and ATP (3 mmol/l). Calphostin C, a potent inhibitor of protein kinase C, inhibited Ca2+/ATP-dependent histamine release by approximately 60%. At the same concentration, calphostin C inhibited by 95% protein kinase C activity in the crude extract obtained from rat mast cells. It was suggested that protein kinase C activation took place in the Ca2+/ATP-dependent histamine release from permeabilized rat mast cells.

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