Vasoactive agents and the mesenteric microcirculation.

Vasoactive agents are known to have a variety of effects on the dynamics of the mesenteric microcirculation. We compare and contrast the effects of both vasodilators and vasoconstrictors on capillary filtration coefficient, vascular permeability, tissue oxygen tension, and microvascular pressure. The various methodologies used to determine the above quantities are discussed, as well as the limitations and advantages of each approach. Discrepancies between the results obtained with particular classes of vasoactive agents are discussed relative to both dosage and route of administration. In addition, data obtained for each parameter using both whole-organ and in vivo microscopic techniques are reconciled relative to the characteristics of each approach. Experimental designs are proposed that may help minimize future inconsistencies in the data, as well as maximize the relative advantages of available techniques.