Effect of hypoxia on feline intestinal capillary permeability

The multiple-indicator dilution technique was used to investigate the permeability characteristics of capillaries in the cat small intestine during hypoxia. Reducing the arterial oxygen tension from 108 to 35 mmHg for 10 min increased the calculated equivalent pore radius of intestinal capillaries from 59 to 67 A. This effect was sustained for at least 15 min after the hypoxic episode. Hypoxia did not alter intestinal lymphatic protein clearance. Thus, the dimensions of the large pores did not change. This study demonstrates that 10 min of severe hypoxia increases vascular permeability in the small intestine and that this change occurs only in the small pores and is sustained, at least briefly, after restoration of normoxia. Hypoxia does not significantly change the permeability to macromolecules.