胆碱能信号通路及离子通道介导精氨酸对结肠平滑肌收缩的促进作用

Aim To investigate the effects of L-arginine on spontaneous contraction of rat colon and the relative mechanisms. Methods An organ bath system was use to measure the spontaneous contraction of both longitudinal smooth muscle strips(LMS)and circular muscle strips(CMS). Whole-cell voltage-clamp techniques were applied to observe the alterations in currents of L-type voltage-dependent Ca2+ channels(VDCCs), and voltage-gated K+ channel(Kv)in single smooth muscle cells(SMCs)from rat colon. Results L-Arginine(1 mmol·L-1)significantly enhanced the spontaneous contraction of both LMS and CMS. The excitatory response to L-arginine was remarkably attenuated by tetrodotoxin(1 mmol·L-1)and atropine(1 mmol·L-1), antagonist of muscarinic ACh receptor(mAChR). However, the inhibitor of nitric oxide(NO)synthesis L-NNA(1 mmol·L-1)failed to block the action of L-Arginine. Furthermore, whole-cell patch-clamp recordings showed that L-arginine activated VDCCs and inhibited Kv channels on SMCs. Conclusions L-Arginine exerts an excitatory effect on colonic motility in a nitric oxide(NO)-independent manner and the stimulatory action of L-arginine is partly mediated by mAChR. In addition, VDCCs and Kv channels are both involved in L-arginine-induced excitation.