Specificity of C-type and atrial natriuretic peptides in human blood vessels

We investigated the actions of the two structurally similar but genetically distinct endothelium-derived vasoactive natriuretic peptides, C-type natriuretic peptide (CNP) and atrial natriuretic peptide (ANP), upon isolated human internal mammary arteries and saphenous veins. Based upon previous studies in canine arteries and veins, we hypothesized that CNP would selectively cause relaxation of human veins while ANP would be selective for human arteries. Rings with and without endothelium of human internal mammary arteries and saphenous veins from patients under going coronary artery bypass grafting were suspended for measurement of isometric force in an organ chamber. CNP caused significant concentration-dependent relaxations in saphenous veins with and without endothelium contracted with phenylephrine (10−6 M). In marked contrast, ANP caused no relaxation in saphenous veins either with or without endothelium. In rings of internal mammary arteries, ANP caused significant concentration-dependent relaxation...