Differential regional hemodynamic effects of corticotropin in conscious sheep.

The regional hemodynamic effects of 5 days of intravenous infusion of corticotropin (ACTH) (5 micrograms/kg per day) were examined in conscious sheep (n = 8). Mean arterial pressure increased from 81 +/- 2 to 93 +/- 3 mm Hg (P < .001) on day 2 of ACTH and remained at this level during the infusion. Cardiac output increased from 5.13 +/- 0.19 to 6.06 +/- 0.33 L/min (P < .01) because of an increase in stroke volume from 65 +/- 4 to 79 +/- 8 mL per beat (P < .01); heart rate remained unchanged. ACTH did not alter total peripheral conductance but had differential effects on regional conductances. Mesenteric conductance fell from 5.8 +/- 0.2 to a minimum of 4.9 +/- 0.3 (mL/min)/mm Hg (P < .05), and renal conductance increased from 3.5 +/- 0.3 to 4.6 +/- 0.3 (mL/min)/mm Hg (P < .001). There was a small increase in iliac conductance (P < .05) and no change in coronary conductance. Mesenteric and iliac conductances fell progressively over 24 to 48 hours, whereas renal conductance increased rapidly after 3 hours of ACTH, reaching a maximum after 6 hours. Renal blood flow was increased during ACTH infusion from 278 +/- 18 to 403 +/- 23 mL/min (P < .001); mesenteric blood flow was unchanged; there was a small increase in iliac blood flow (P < .01); and coronary blood flow increased (P < .05), paralleling the change in cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)