Plasma urocortin 1 in sheep: regional sampling and effects of experimental heart failure

Although urocortin 1 (Ucn-1) has been reported to circulate in human plasma and be raised in heart failure, little, if any, information is available regarding the source of circulating Ucn-1. Accordingly, we have performed trans-organ arteriovenous sampling for measurement of Ucn-1 concentration in anesthetized sheep before and after development of pacing-induced heart failure. Arterial plasma Ucn-1 levels measured 15.2 +/- 0.5 pmol/L in normal sheep and increased significantly following development of heart failure to 19.1 +/- 1.6 (p < 0.05). Small but significant positive arteriovenous gradients were observed across the hepatic and renal tissue beds in both states, with rises across the hind limb significant in normal animals and across the head in heart failure. This is the first report identifying sources of circulating Ucn-1.