Effect of the ecto-ATPase inhibitor, ARL 67156, on the bovine chromaffin cell response to ATP

Abstract

Bovine chromaffin cells contain an ecto-ATPase ( K m=1.57±0.27×10 −4 M) which can hydrolyze ATP present in the culture media. ARL 67156 is a competitive inhibitor of this ATPase ( K i=2.55±1.36×10 −7 M). A small increase in potency (threefold) is seen when ARL 67156 is included during measurement of ATP-stimulated inositol phosphate formation. ARL 67156 also acts on chromaffin cell P2Y receptors to increase inositol phosphate formation (EC 50=4.9×10 −5 M). It is useful as an ecto-ATPase inhibitor in studies with bovine chromaffin cells since it exhibits a 300-fold selectivity for the ecto-ATPase versus the P2Y receptor.