OBJECTIVETo study the effect on synthesis of nitric oxide in myocardium by local cryoablation and to investigate its mechanism.

METHODSMyocardium 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.

RESULTSNitric 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.

CONCLUSIONNitric oxide and its synthesis enzyme in myocardium decrease after cryoablation.