The ATP4- receptor of rat mast cells.
The concentration-dependence on exogenous ATP of activation and inhibition of mast-cell histamine secretion, phosphatidylinositol labelling and leakage of metabolites shows that all these functions are regulated by the free acid ATP4-. Maximal histamine secretion and phosphatidylinositol labelling occur with ATP4- at approx. 2 microM, but higher concentrations, which cause inhibition of secretion and phosphatidylinositol labelling, are required to maximize leakage of 32P-labelled metabolites. Both enhancement and inhibition of phosphatidylinositol labelling (due to low and high concentrations of ATP4- respectively) are rapid in onset; histamine secretion is characterized by a delay, especially at low concentrations of ATP4- (approx. 1 microM). Phosphatidylinositol labelling and histamine secretion are dependent on extracellular Ca2+. Metabolite leakage due to the presence of exogenous ATP4- is slow and does not require Ca2+. Of 18 analogues of ATP that were tested, only four were agonists for secretion, and only these four permitted leakage of 32P-labelled metabolites. It is argued that activation and inhibition of histamine secretion, phosphatidylinositol labelling and metabolite leakage are all initiated by ATP4- acting at the same receptor. For mast cells stimulated with ATP4- enhancement of phosphatidylinositol metabolism is not sufficient by itself to cause Ca2+-dependent secretion.
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006636:Histamine Release / Q000187:drug effects; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008407:Mast Cells / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011983:Receptors, Purinergic
D010716:Phosphatidylinositols; D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D000255:Adenosine Triphosphate; D008274:Magnesium; D002118:Calcium