Differing calcium requirements for regulatory effects of ATP, ATP[gamma]S and adenosine on O2 responses of human neutrophils

Abstract

In formyl peptide stimulated human neutrophils the enhancement of O2 responses by ATP and ATP[gamma]S requires extracellular calcium. In contrast, the inhibitory effects of adenosine are independent of a calcium requirement. Rates of O2 generation are not affected by these adenine compounds. Rather, ATP and ATP[gamma]S cause a sustained period of generation whereas adenosine causes an abrupt early termination of the O2 response. The differing calcium requirements for regulatory effects of adenine compounds on O2 responses of stimulated neutrophils suggests that ATP (or ATP[gamma]S) and adenosine may exert their effects at different points in the pathway of signal transduction events.