INHIBITION OF VASODILATATION BY METHYLENE BLUE IN LARGE AND SMALL ARTERIES OF THE DOG HINDLIMB IN VIVO

Abstract

b 1. Injection of acetylcholine (ACh, 0.0005–2 μg/kg) or glyceryl trinitrate (GTN, 0.01–20 μg/kg) into the femoral artery increased femoral artery diameter, femoral blood flow and heart rate, and reduced femoral vascular resistance and systemic arterial blood pressure in anaesthetized dogs. The intravenous (i.v.) injection of ACh (2 μg/kg) produced a small decrease in systemic arterial pressure and an increase in heart rate, but did not dilate the hindlimb vessels. 2. Methylene blue, a guanylate cyclase inhibitor, continuously infused into the femoral artery (10 mg/min), attenuated the increase in femoral artery diameter and femoral blood flow, and the decrease in femoral vascular resistance..