Suppression of maxi-K channel and membrane depolarization by synthetic polycations in single tracheal myocytes.

摘要: Polycationic proteins, e.g., major basic protein from eosinophils or cathepsin G neutrophils, have been shown to increase nonspecific airway responsiveness. Along with several indirect manners of action, polycations were reported contract smooth-muscle strips and raise the cellular Ca2 + concentration as a direct action on smooth muscle. However, mechanistic basis for behavior remains be elucidated. To address this issue, we examined effects synthetic cationic polypeptides poly-l-arginine poly-l-lysine fresh single cells bovine trachea using patch-clamp technique. Both significantly depolarized membrane baseline about − 40 20 mV in dose-dependent manner. The also suppressed whole-cell spontaneous transient outward currents well both conductance (from 130 70 pS) open-state probability (about 25% control values) large-conductance +-dependen...