ABSTRACT
<p><b>AIM</b>To investigate the influence of L-arginine (NO donors, L-Arg) on spontaneous contractions of ileum in mice and study the effects of activation of beta-adrenoceptor on NO-induced inhibition in spontaneous contractions of ileum.</p><p><b>METHODS</b>The method of spontaneous contractions recording was used to investigate the effect of L-NNA, ODQ, Isoprenaline( beta-adrenoceptor agonist) and Propranolol (beta-adrenoceptor antagonist) on NO-induced inhibition in spontaneous contractions of ileum.</p><p><b>RESULTS</b>(1) L-Arg inhibited the spontaneous contractions of ileum and had concentration-response relationship. (2) L-NNA (3 x 10(-4) mol/L), ODQ (3 x 10(-6) mol/L) relieved the inhibitory effect of L-Arg in ileum . (3) Propronalol (3 x 10(-6) mol/L) decreased significantly the inhibitory effect of L-Arg. (4) Iso (1 x 10(-7) mol/L) increased the inhibitory effect of L-Arg. After Iso (1 x 10(-7) mol/L) and Propronalol (3 x 10(-6) mol/L) being coapplied, the inhibitory effect of L-Arg was not changed.</p><p><b>CONCLUSION</b>NOS catalyzed L-Arg and produced NO. NO exerted its inhibitory effect by the cGMP pathway, the activation of beta-adrenoceptor was partly involved in NO-induced relaxation in ileum.</p>