Abstract 2050: Differential Effects of Natriuretic Peptides on Arterial and Venous Coronary Artery Bypass Conduits
Background: Long-term patency of arterial grafts used for coronary bypass grafting (CABG) is superior to that of venous grafts. Natriuretic peptides (NP’s) have a major role in vascular homeostasis. We characterized the effects of NP’s and their receptors (NPR) in commonly used CABG conduits.
Methods: The relaxation and tissue levels of cGMP in response to 3 NP’s (ANP, BNP and CNP) were assessed in pre-contracted segments of internal mammary artery (IMA), radial artery (RA) and saphenous vein (SV) obtained from the same patients (n=12) in the absence/presence of the LY83583 (Guanylyl Cyclase inhibitor) or L-NAME (Nitric Oxide synthase inhibitor). NPR expression was assessed using immunohistochemistry and Western blotting.
Results: Results are summarized in the Tables⇓. Maximal relaxation of the IMA and RA to ANP, BNP and CNP were similar and greater than SV, correlating with increased tissue levels of cAMP in both arterial conduits. Relaxation response to all 3 NP’s were nearly abolished in the presence of LY83583. Exposure of the conduits to L-NAME resulted in only a modest blunting of the relaxation response to the NP’s. NPR-A, NPR-B and NPR-C were strongly expressed in both the endolethium and vascular smooth muscle layer of the IMA and RA and significantly less in SV.
Conclusion: NP’s are potent vasodilators of the IMA and RA but not the SV. The relaxation response is mediated via NPRs/cGMP and the Nitric Oxide systems. These observations provide additional insight into the potential physiological mechanisms underlying the superior patency of arterial conduits and may form a basis for potential therapeutic interventions aimed to improve vein grafts performance.