Ethacrynic acid inhibitable Ca2+ and Mg2+-activated membrane adenosine triphosphatase in rat mast cells.

ABSTRACT

A crude plasma membrane fraction from the homogenate of purified rat mast cells demonstrates a high degree of Ca2+-dependent and Mg2+-dependent adenosine triphosphatase (ATPase) activity. The microsomal and mitochondrial fractions show negligible amounts of the Ca2+ and Mg2+-activated ATPases. The broad ATPase inhibitor, ethacrynic acid, effectively blocks the mast cell ATPase activity while ouabain demonstrates little inhibitory effect. Correspondingly, ethacrynic acid inhibits histamine release from antigen-challenged mast cells while ouabain does not. Both ATPase inhibition and histamine release inhibition by ethacrynic acid require the presence of the olefinic bond in the ethacrynic acid molecule.