Reversible and selective antagonism by suramin of ATP‐activated inward current in PC12 phaeochromocytoma cells

Abstract

1 The effects of suramin on an adenosine 5′-triphosphate (ATP)- activated inward current were investigated in PC12 phaeochromocytoma cells with whole-cell voltage-clamp techniques. 2 Suramin (30 to 300 μm) inhibited the ATP-activated current in a dose-dependent manner. The inhibitory effects were reversible and competitive. 3 Suramin also suppressed the current activated by adenosine 5′-0-(3-thio triphosphate) but did not affect the current activated by nicotine. Suramin did not affect the suppression of a K current induced by methacholine. 4 The results suggest that suramin antagonizes the ATP-receptor-operated membrane current reversibly and selectively.