Figure 5. Generation of nitric oxide is required for the anti‐fibrillatory effect of carbamylcholine .

A, the anti‐fibrillatory action of carbamylcholine (CCh, 200 nmol l⁻¹) is abolished by the non‐specific nitric oxide synthase (NOS) inhibitor l‐NA (10 μmol l⁻¹) and reversed by addition of l‐arginine (l‐Arg, 5 mmol l⁻¹, ***P < 0.001). This effect is lost upon wash out of all drugs. B, soluble guanylate cyclase (sGC) inhibition by ODQ (10 μmol l⁻¹, n = 6) results in a significant reduction in ventricular fibrillation threshold (VFT) which cannot be increased by the addition of CCh. C and D, nNOS inhibition by AAAN (10 μmol l⁻¹) is able to abolish and prevent the increase in VFT in response to CCh perfusion (n = 6 per each series, *P < 0.05, **P < 0.01).