ATP‐activated Ca2+‐permeable channels in rat peritoneal macrophages

Abstract
The patch‐clamp technique was used to study mechanisms of ATP‐induced Ca2+ influx in rat peritoneal macrophages. The experiments on whole‐cell and patch membranes have shown that extracellular ATP activates channels permeable to di‐ and monovalent inorganic cations. Ratios of unitary channel conductances in 105 mM Ca2+, Sr2+, Mn2+, Ba2+ and normal sodium solutions were 1.0, 0.95, 0.75, 0.55 and 0.85, respectively. The channels could open in the presence of non‐hydrolyzable GTP analogues in artificial intracellular solution. The data are consistent with the hypothesis that a GTP‐binding protein is involved in receptor‐to‐channel coupling.