Normalization of coronary microvascular reactivity and improvement in myocardial perfusion by surgical vascular endothelial growth factor therapy combined with oral supplementation of l-arginine in a porcine model of endothelial dysfunction

Abstract

Objective: Vascular endothelial growth factor acts in part through nitric oxide release, the availability of which is decreased in endothelial dysfunction associated with advanced coronary artery disease. This could explain the relatively disappointing results of vascular endothelial growth factor therapy in clinical studies compared with animal studies. We examined the influence of L-arginine supplementation to vascular endothelial growth factor therapy on myocardial microvascular reactivity and perfusion in a porcine model of endothelial dysfunction.

Methods: Twenty-four pigs were fed either a normal (NORM, n = 8) or high-cholesterol diet with (CHOL-ARG, n = 8) or without (CHOL, n = 8) L-arginine. All pigs underwent ameroid placement on the circumflex artery and then 3 weeks later received surgical vascular endothelial growth factor treatment. Four weeks after treatment, endothelial-dependent coronary microvascular responses and lateral myocardial perfusion were assessed. Endothelial cell density was determined by means of immunohistochemistry. Vascular endothelial growth factor, endothelial nitric oxide synthase, and Akt levels were determined by means of immunoblotting.

Results: Pigs from the CHOL group showed endothelial dysfunction in the circumflex territory, which was normalized by L-arginine supplementation. Vascular endothelial growth factor treatment was ineffective in the CHOL group (circumflex/left anterior descending coronary artery blood flow ratios: 0.95 [rest] and 0.74 [pace] before-after treatment; P < .05 compared with the NORM group). Addition of L-arginine restored the angiogenic effect of vascular endothelial growth factor (ratios: 1.13 [rest] and 1.20 [pace]; P < .05) and was associated with increased endothelial cell density, as well as vascular endothelial growth factor, endothelial nitric oxide synthase, and Akt protein levels in the ischemic territory.

Conclusions: L-Arginine supplementation can restore normal endothelium-dependent vasorelaxation and angiogenic response to vascular endothelial growth factor in a swine model of chronic myocardial ischemia with hypercholesterolemia-induced endothelial dysfunction. These findings suggest a putative role for L-arginine in combination with vascular endothelial growth factor therapy for end-stage coronary artery disease.