A. The anti-fibrillatory action of carbamylcholine (CCh, 200nmol/L) is abolished by the non-specific nitric oxide synthase (NOS) inhibitor L-NA (10μmol/L) and reversed by addition of L-arginine (L-Arg 5mmol/L, ***p<0.001). This effect is lost upon wash out of all drugs. B. Soluble guanylate cyclase (sGC) inhibition by ODQ (10μmol/L, n=6) results in a significant reduction in ventricular fibrillation threshold (VFT) which can not be increased by the addition of CCh. C/D. Neuronal NOS inhibition by AAAN (10μmol/L) is able to abolish and prevent the increase in VFT in response to CCh perfusion (n=6/each series, *p<0.05, **p<0.01)