Quantitative studies of microcirculatory structure and function. III. Microvascular hemodynamics of cat mesentery and rabbit omentum.

We made simultaneous measurements of intravascular pressure and red blood cell velocity for vessels which make up the modular configuration of microvascular networks in mesentery and omentum. An analysis of these variables and the computed volumetric flow rates is presented for arterioles which had a maximum diameter of 56 micrometer through the "true capillaries" (typically 7 micrometer for mesentery and 8 micrometer for omentum) to 56-micrometer venules. The spatial variance of pressure and flow is related to topographical features of each network. Vascularization statistics for each network are presented and demonstrate a unique ratio of potential microvascular exchange area to module planar area, with values of 0.71 +/- 0.22 (SD) for omentum and 0.19 "/- 0.03 (SD) for mesentery. Analysis of the volumetric flow rate for each module demonstrates a linear relationship to the planar area of tissue serviced by each modular network. In situ perfusion rates of 1180 ml/min per 100 g and 105 ml/min per 100 g were determined for omentum and mesentery, respectively. The hemodynamic resistance of the omental and mesenteric circuitry was evaluated, and in the case of the omentum, found to be inversely proportional to the planar area of the module. The arterial to venous distribution of pressure and flow for the mosaic of contiguous modules in omentum and mesentery is described and related to the deployment of parallel and serial microvessels of each network.