[Nicotine regulates large conductance ca2+ activated K+ channels in rat coronary arterial smooth muscle cells].

ABSTRACT

OBJECTIVE: The present study was to explore signaling mechanisms underlying nicotine-induced inhibition of large-conductance calcium-activated potassium channels (BK(Ca)). METHODS: 8 week male Wistar rats were divided randomly into saline group and nicotine group and received respectively injection with saline or nicotine (Sigma, Shanghai, China) at 2 mg/(kg x d) for 21 days. Coronary vascular smooth muscle cells were dissociated enzymatically. Dissociated smooth muscle cells were interfered with CPT-cAMP (100 micromol/L) or forskolin (10 micromol/L). The signal channel open dwell-time (To), close dwell-time (Tc) and open probability (Po) were recorded. RESULTS: CPT-cAMP or forskolin significantly prolonged To, shorten Tc and increased Po in saline group (P < 0.01). But in nicotine group To, Tc and Po did not been changed. CONCLUSION: This phenomenon may serve as a physiological mechanism that nicotine inhibits BK(Ca) channel activity to increase via cAMP/PKA-dependent pathway.