Generation of an endothelium-derived relaxing factor-like substance in bovine tracheal smooth muscle

The mechanism of the accumulation of guanosine 3',5'-cyclic monophosphate (cGMP) induced by carbachol was investigated in bovine tracheal smooth muscle preparations. The effects of carbachol on cGMP were prevented with methylene blue, hemoglobin, or atropine, indicating that the increase of cGMP induced by carbachol is due to the activation of muscarinic cholinergic receptors and is mediated by the stimulation of soluble guanylyl cyclase. The elevation in cGMP induced by carbachol was also inhibited by the superoxide anion-generating compound pyrogallol (100 microM). This inhibition was reversed by superoxide dismutase (100 U/ml). Furthermore, NG-methyl-L-arginine (100 microM) and NG-nitro-L-arginine (3 microM) inhibited cGMP accumulation induced by carbachol, and this was reversed by the addition of L-arginine (1 mM). These results suggest that an endothelium-derived relaxing factor-like substance is generated in the course of carbachol-induced cGMP accumulation in bovine tracheal smooth muscle and that the precursor of this substance is L-arginine.