Role in Sustained Arteriolar Dilatation Distal to a Coronary Stenosis

This study tested the hypothesis that myocardial tissue acidosis is responsible for maintenance of reduced arteriolar tone distal to a severe coronary arterial stenosis. Domestic swine (n=10) were instrumented with a coronary arterial stenosis that reduced vessel diameter 80%. Measurements of hemodynamic indexes were made 1) before stenosis, 2) at 5, 20, and 60 minutes after stenosis placement, and 3) after each of three, 20-minute NaOH infusions (0.05 M, 0.1 M, and 0.5 M) distal to the stenosis (group 1). Intracellular pH at the end of 30 minutes of 0.5 M NaOH infusion distal to the stenosis was measured in a second group (n=6) of swine (group 2). After stenosis placement in group 1, endocardial blood flow declined significantly, and evidence of regional acidosis (increased coronary venous Pco2 and decreased coronary