Direct measurements of the dextran-dependent calcium uptake by rat peritoneal mast cells.
The metallochromic indicator murexide has been used to monitor calcium concentration changes during the dextran-induced, phosphatidylserine-dependent degranulation of rat peritoneal mast cells. The dextran-induced Ca2+-uptake showed an absolute dependence on the presence of phosphatidylserine. The extent of Ca2+-uptake increased with phosphatidylserine in a concentration-dependent manner. At 25 degrees C the half-life of the uptake process equalled 35 +/- 5 s. Exposure of the mast cells to dextran in the presence of Ca2+, but in the absence of phosphatidylserine, desensitized the cells. The subsequent addition of phosphatidylserine failed to restore the Ca2+-uptake activity. However, the Ca2+-ionophore A23187 did promote Ca2+ uptake by the cells without PS.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003911:Dextrans / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008407:Mast Cells / Q000378:metabolism*; D009114:Murexide / Q000494:pharmacology; D010718:Phosphatidylserines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D003911:Dextrans; D010718:Phosphatidylserines; D000001:Calcimycin; D009114:Murexide; D002118:Calcium