AJP - Gastrointestinal and Liver Physiology, Vol 238, Issue 6 478-G484, Copyright © 1980 by American Physiological Society
Intrinsic control of colonic blood flow and oxygenation
P. R. Kvietys, T. Miller and D. N. Granger
In a denervated autoperfused dog colon preparation, arterial perfusion
pressure, venous outflow pressure, blood flow, and arteriovenous O2
difference were measured during graded arterial pressure alterations,
arterial occlusion, venous pressure elevation, venous occlusion, and local
intra-arterial infusion of adenosine. As perfusion pressure was reduced
from 100 to 30 mmHg, colonic blood flow decreased and arteriovenous O2
difference increased. Although blood flow was not autoregulated O2 delivery
was maintained within 10% of control between 70 to 100 mmHg and then
decreased with further reduction in perfusion pressure. Arterial occlusion
(15, 30, and 60 s) resulted in a postocclusion reactive hyperemia; the
magnitude of the hyperemia was directly related to the duration of
occlusion. Venous occlusion resulted in a postocclusion reactive hypoemia.
Elevation of venous pressure from 0 to 20 mmHg increased vascular
resistance, O2 extraction, and the capillary filtration coefficient, but
decreased O2 delivery. Infusion of adenosine decreased vascular resistance
and O2 extraction, but increased O2 delivery. These data suggest that both
metabolic and myogenic mechanisms are involved in the control of colonic
blood flow and oxygenation.
