Pretreatment with NG-nitro-L-arginine methyl ester (L-NAME, 0.5 mmol/L), a nitric oxide (NO) synthase inhibitor, did not affect the effects of GST on AV node cells.

• （4）NO合酶阻断剂L-NAME(0.；5 mmol/L)对GST的效应无影响。