Cerebral production of adrenomedullin after hypothermic cardiopulmonary bypass in adult cardiac surgical patients

Adrenomedullin is a potent vasodilatory peptide originally identified in hu man pheochromocytoma. Plasma adrenomedullin increases during and after card iopulmonary bypass (CPB). However, the site at which production of adrenome dullin is augmented has not been identified. In the present study, we exami ned the contribution of the cerebral vasculature to the production of adren omedullin in patients before, during, and after CPB. Ten patients undergoin g coronary artery bypass grafting with mild hypothermic CPB were studied. C erebral blood flow was measured using the Kety-Schmidt method before, durin g, and after CPB. Plasma adrenomedullin concentrations from radial artery a nd internal jugular bulb blood were measured by radioimmunoassay, and cereb ral adrenomedullin production was evaluated. Adrenomedullin production in t he cerebral vasculature was significantly enhanced after CPB and correlated with aortic cross-clamping time. The cerebral adrenomedullin production ma y contribute to the increased plasma level of adrenomedullin after CPB. Imp lications: Plasma adrenomedullin has been reported to Increase in humans af ter cardiac surgery involving cardiopulmonary bypass. In this study, we dem onstrated that cerebral adrenomedullin production may contribute to the inc reased plasma level of adrenomedullin after cardiopulmonary bypass.