Streptozotocin, an inducer of NAD⁺ decrease, attenuates M-potassium current inhibition by ATP, bradykinin, angiotensin II, endothelin 1 and acetylcholine in NG108-15 cells

The M-potassium current was inhibited by bath application of 100 μM ATP, 10 nM bradykinin, 100 nM angiotensin II and 100 nM endothelin 1 as well as by 10 μM acetylcholine in an m1-muscarinic acetylcholine receptor-transformed NG108-15 cell line. The inhibition of M-current was attenuated in cells pretreated with 5 mM streptozotocin for 5-15 h and restored by simultaneous incubation with 5 mM nicotinamide. The results suggest that signal transduction from these five different receptors to M channels shares a common pathway which is susceptible to a streptozotocin-induced decrease in cellular NAD⁺ content.