Transmural pressure was measured in the main trunk and in a proximal branch of the mesenteric artery from normotensive dogs. Dopamine and noradrenaline content were determined in both mesenteric arterial segments. For each vessel transmural pressure values and dopamine and noradrenaline content were plotted for calculation of linearity of regression. A positive correlation was found between transmural pressure values and catecholamine content in both segments of the mesenteric artery; i.e. in the main trunk and in the proximal branch. These findings suggest a reciprocal regulation between structure/function of these blood vessels and their sympathetic innervation.