REGIONAL VASCULAR EFFECTS OF RHB1.1, A HEMOGLOBIN-BASED OXYGEN CARRIER

The goals of this study were to determine the effects of recombinant h uman hemoglobin (rHb1.1, 1, g/kg i.v.) on systemic hemodynamics, regio nal blood flows, and regional vascular resistances in rats. Cardiac ou tput (GO) and regional blood flow in 13 tissues were determined by usi ng the radiolabeled-microsphere method during halothane anesthesia. Mi crospheres were injected at three time points: before (control, t = 0) , t = 30 [10 min after a 20-min infusion of vehicle (diluent) or rHb1. 1], and at t = 120 min. Infusion of diluent did not alter CO, heart ra te (HR), mean arterial pressure (MAP), or systemic vascular resistance (SVR) and had minimal effects on regional blood flows. Infusion of rH b1.1 did not alter CO or HR but did increase MAP and SVR compared with diluent. Infusion of rHb1.1 increased blood flow to the heart and dec reased blood flow to the gastrointestinal tract (GIT) and liver. Compa red with the corresponding values in the diluent-treated rats, resista nce was increased after rHb1.1 in spleen, kidney, and hepatic artery. In conclusion, rHb1.1 administration increased MAP and SVR. The vasoco nstriction was heterogeneous and was associated with increased coronar y blood flow and with increased regional resistance in kidney, spleen, and hepatic artery, compared with diluent-infused controls.