Impairment of aortal tone by no flow-reflow conditions and its partial amelioration by mannitol

Background. Although postischemic cardiac or pulmonary dysfunction can rela te to the impact of remotely generated oxygen stress mediators on the heart , their direct effect on the vascular bed remains unresolved. Thus, we test ed these remote effects in an ex-vivo double organ model. Methods. After stabilization With Krebs-Henseleit solution, isolated rat li vers were either perfused or made ischemic for 2 hours. Aortic rings were s tabilized, immersed in postischemic liver perfusates and their functions we re tested. Some organs originated from donors fed with tungstate, whereas o thers had mannitol (0.25 g/kg) in the buffer. Results. Incubation of aortic rings with postischemic hepatic effluent resu lted in protracted contraction. Spasm was slightly lesser when the livers w ere pretreated with tungstate or exposed to mannitol, but worse in pretreat ed rings. The return to basal tone was abrupt in all ischemia-reperfusion a ortae. The response of the rings to phenylephrine under the influence of th e ischemia-reperfusion hepatic effluent was deficient. Mannitol prevented m ost abnormal responses. Conclusions. Aortal tone impairment can occur by direct influence of the is chemia-reperfusion liver. It cannot be attributed entirely to xanthine oxid ase, but also to other hepatic-released factors. (C) 2000 by The Society of Thoracic Surgeons.