Effect of local arterial hypotension on cat intestinal capillary permeability.

The effects of local arterial hypotension on lymph flow, lymphatic protein flux, and capillary permeability were analyzed in an isolated vascularly perfused cat ileum preparation. Reductions in perfusion pressure to 30-40 mmHg (60 min) resulted in a lowering of lymph flow and an increase in the lymph to p lasma protein concentration ratio. Release of the partial arterial occlusion caused lymph flow and lymph to plasma protein concentration ratio to increase above their control values. Venous outflow pressure was then increased in 10 mmHg increments to 30 mmHg. The capillary osmotic reflection coefficient was estimated from the relationship between lymph to plasma protein concentration ratio and lymph flow. Values of the osmotic reflection coefficient for total proteins and individual protein fractions were significantly lower than control values. The results of this study indicate that 1 hr of regional ischemia significantly increases the permeability of intestinal capillaries. The increased capillary permeability accounts, at least in part, for the enhanced capillary filtration and interstitial fluid accumulation which occurs in the posthypotensive small intestine.