Blood flow limitations of solute transport across the visceral peritoneum

In a previous study, no limitations to urea transfer across the parietal peritoneum were demonstrated with decreases in local blood flow of 70%. It was hypothesized that the visceral peritoneum would have similar characteristics. To address this problem at the tissue level, diffusion chambers were affixed to the serosal side of the stomach, cecum, or liver of anesthetized rats (n = 6 each tissue), and solutions containing 14C urea were placed in the chamber. During each experiment, the local chamber blood flow was measured with laser Doppler flowmetry, and, simultaneously, the disappearance of the tracer versus time was determined under three conditions: control, after 60 to 70% blood flow reduction, and postmortem (flow = 0). The results showed no difference in the urea mass transfer coefficient (MTC; mean +/- SEM; cm/min x 10[3]) between control and blood flow reduction for the stomach (4.0 +/- 0.4 versus 3.6 +/- 0.3) or for the cecum (4.6 +/- 0.3 versus 4.0 +/- 0.3). However, the MTC was significantly decreased by local blood flow reduction in the liver (5.4 +/- 0.2 versus 2.6 +/- 0.2). Postmortem data demonstrated significant reductions in the MTC with blood flow equal to zero. It is concluded that a 60 to 70% blood flow reduction from control values does not limit solute transperitoneal transfer in the hollow viscera but causes significant changes in the mass transfer across the liver surface. Because the liver makes up only a small portion of the effective exchange area, overall transperitoneal solute transfer should not be greatly affected by significant decreases in blood flow.