[Effect of nitric oxide on the myoelectric activity of sphincter of Oddi and arterial blood pressure of rabbit].

Thirty-two rabbits were used to investigate the effect of nitric oxide (NO) on the myoelectric activity of the sphincter of Oddi (SO) and arterial blood pressure. Intravenous infusion of NG-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthase (NOS), caused increase in SO phasic wave amplitude and arterial blood pressure. The increase in SO phasic wave amplitude by infusion of L-NNA was reversed by L-arginine, but arterial blood pressure remained at a high level. It was observed that SO phasic wave amplitude, frequency and arterial blood pressure were significantly decreased by intravenously infusion of sodium nitroprusside (SNP), a substance producing NO. These observations suggest that (1) NO inhibits the resting activity of SO and modulates relaxation of vascular smooth muscle; (2) different tissues show different responses to L-NNA and L-arginine.