ROLE OF A LYMPHATIC-SYSTEM IN GLUCOSE-ABSORPTION AND THE ACCOMPANYINGMICROVASCULAR HYPEREMIA

In this study we evaluated the importance of a functional intestinal l ymphatic system on changes in arteriolar and venular blood oxygen cont ent, vasodilation, and elevation of venous blood osmolarity during glu cose absorption. Glucose absorption was associated with a doubling of the arteriovenous oxygen difference [(A-V)O-2], a 50 mosM increase in venous blood osmolarity, and 17% dilation of the intermediate-diameter arterioles. After the lymph vessels were mechanically blocked with mi neral oil, glucose absorption again doubled the (A-V)O-2, indicating t hat glucose was absorbed without a functional lymphatic system. Furthe rmore, venous blood osmolarity and arteriolar diameter increased simil arly with and without a functional lymphatic system. This study indica tes that even though the lymphatic system likely facilitates distribut ion of hypertonic material in the bowel wall during absorption, blocka de of the lymphatics did not appreciably hinder vasodilation, glucose absorption, changes in intravascular oxygen content, or the elevation of tissue hyperosmolarity, as judged by the tonicity of the venular bl ood. Therefore, passage of materials absorbed or released in the mucos a to the submucosa through venular blood flow may be very important to the mechanism of absorptive hyperemia.