AJP - Gastrointestinal and Liver Physiology, Vol 254, Issue 5 695-G701, Copyright © 1988 by American Physiological Society
Thromboxane synthesis inhibitors and postprandial jejunal capillary exchange capacity
M. J. Mangino and C. C. Chou
Department of Physiology, Michigan State University, East Lansing 48824-1101.
The effects of thromboxane synthesis inhibitors (imidazole and U 63557A;
Upjohn) and the cyclooxygenase inhibitor, mefenamic acid, on jejunal
capillary filtration coefficients (Kfc) were determined in dogs before and
during the presence of predigested food in the jejunal lumen. The jejunal
Kfc increased significantly soon after the placement of a predigested test
food containing all major constituents of diet. The Kfc remained elevated
as long as the food was present in the lumen (15 min). Mefenamic acid (10
mg/kg iv) did not significantly alter resting jejunal Kfc or alter the
food-induced increase in Kfc. Imidazole (5.0 mg/min ia) or U 63557A (5.0
mg/kg iv) per se significantly increased jejunal Kfc. Placement of digested
food further increased the Kfc to levels significantly higher than those
observed before administration of the two thromboxane synthase inhibitors.
Production of thromboxane B2 by jejunal tissue was significantly reduced
and 6-ketoprostaglandin F1 alpha (the stable hydrolysis product of
prostacyclin) production was significantly increased after administration
of U 63557A. Our study indicates that the relative production of endogenous
thromboxanes and other prostanoids modulates jejunal capillary exchange
capacity in the absence or presence of digested food in the jejunal lumen.
