ABSTRACT
<p><b>OBJECTIVE</b>To study the effect on synthesis of nitric oxide in myocardium by local cryoablation and to investigate its mechanism.</p><p><b>METHODS</b>Myocardium was cryoablated locally by a probe cooled to -60 degrees C and rewarmed by normal salt solution, nitric oxide and its synthesis enzyme were measured before and after cryoablation. L-arginine or methylene blue was added before and during cryoablation and the effect of these drugs on synthesis of nitric oxide was studied.</p><p><b>RESULTS</b>Nitric oxide and its synthesis enzyme decreased after cryoablation; L-arginine preserved the synthesis of nitric oxide and methylene blue inhibited the synthesis of nitric oxide. However, nitric oxide in serum did not change.</p><p><b>CONCLUSION</b>Nitric oxide and its synthesis enzyme in myocardium decrease after cryoablation.</p>