Does TAME induced contraction involve an endothelium dependent nitric oxide-cyclic GMP mediated pathway?

Two enzyme inhibitors namely L-NAME, a nitric oxide synthase (NOS) inhibitor and methylene blue, a guanylate cyclase inhibitor, were used to elucidate whether N-alpha-tosyl L-arginine methyl ester (TAME)-induced contractions in toad intestinal rings in vitro are mediated through a nitric oxide (NO)- cyclic GMP (c-GMP) pathway. Moreover, a NO precursor, L-arginine was also used to investigate its effect on TAME-induced contractions. Our findings provide evidence that TAME-induced contractions have both an endothelium-dependent and an endothelium-independent component. Based on our findings we now propose that TAME induced contraction involves an endothelium-dependent component mediated through NO and c-GMP.