Response of human artery, vein, and cultured smooth muscle cells to atrial and C-type natriuretic peptides

Objectives: We determined the response of intracellular cyclic GMP in human arteries and veins and in smooth muscle cells cultured from these vessels to C-type natriuretic peptide in comparison with atrial natriuretic peptide. Design: Repeated-measures analysis of concentration-response curves. Setting: Anesthesia research laboratory. Subjects: Vascular smooth muscle cells from human blood vessels obtained with Institutional Review Board approval and patient consent. Measurements and Main Results: Segments of internal mammary artery and saphenous vein were obtained from patients undergoing coronary artery bypass surgery. Smooth muscle cells were cultured from these vessels. Concentration-response curves of intracellular cyclic GMP were determined and analyzed by two-way analysis of variance with repeated measures. In segments of intact saphenous vein, C-type natriuretic peptide was significantly more effective than atrial natriuretic peptide (10-fold increase in cyclic GMP in response to 1 μM of C-type natriuretic peptide vs. six-fold increase in cyclic GMP in response to 1 μM of atrial natriuretic peptide, p < .05). In rings of intact internal mammary artery, 1 μM of atrial natriuretic peptide (26-fold increase in cyclic GMP over basal value) was more effective than 1 μM of C-type natriuretic peptide (three-fold increase in cyclic GMP over basal value, p < .05). In cultured cells from these vessels, the pattern of response to C-type natriuretic peptide and atrial natriuretic peptide was the same as in the intact vessels. Conclusions: These results indicated that human smooth muscle cells in arteries and veins express both forms of natriuretic peptide receptors but that atrial natriuretic peptide acts primarily on the artery and C-type natriuretic peptide acts predominately on the vein. Increased concentrations of C-type natriuretic peptide could contribute to venous pooling in septic shock.