Figure 6.

Effects of sulfur-containing amino acids in the presence of SNP and L-NA on the membrane potential of murine proximal colon. (a–c) SNP induced large hyperpolarization in colonic smooth muscles. Methionine, homocysteine and cysteine partially restored membrane potentials hyperpolarized by SNP (10 μM). (d–f) L-NA (100 μM) caused large depolarization. Methionine, homocysteine and cysteine further depolarized membrane potentials in the presence of L-NA, but these responses were significantly less than that observed in the absence of L-NA. Dashed lines in each panel indicate membrane potentials before the addition of drugs.