Redistribution of cardiac output during localized granulomatous inflammation and the effect of methysergide in anesthetized rats.

The distribution of cardiac output (CO) to different organs and tissues was determined by the radioactive microsphere technique in anesthetized rats 3, 5, 7, and 10 days after subcutaneous implantation of carrageenan-impregnated sponges to induce granulomatous inflammation. Distribution of CO to organs which usually respond to stress (heart, spleen, adrenals) was increased during the acute-subacute inflammatory response, at the expense of the distribution to the head, brain, abdominal muscle, and hind legs. Later decreases were seen in distribution of CO to the kidneys, tail, forelegs, and urogenitals. Vascular-related skin temperature (measured by thermography) and distribution of CO to the back skin generally showed a decrease, particularly to the skin covering the granuloma. This latter decrease was reversed by systemic treatment with methysergide (40 mg/kg) which also increased distribution of CO to the head and decreased that to the liver. Most of the effects observed can be attributed to the extra burden on the circulation presented by the highly vascularized granuloma tissue and/or to the release of 5-hydroxytryptamine, but may differ from changes in conscious rats.