Effects of dobutamine and dopexamine on hepatic micro- and macrocirculation during experimental endotoxemia: An intravital microscopic study in the rat

Objective: To test the effects of dobutamine and dopexamine an hepatic port al and sinusoidal blood flow in a model of normodynamic endotoxemia. Design: Randomized, controlled trial. Setting: Experimental laboratory. Subjects: Male Wistar rats (250-350 g). Interventions: A total of 40 male Wistar rats were randomized into four gro ups: a control group, which only received Ringer's solution; an endotoxin g roup, which received a continuous infusion of 2 mg/kg body weight (bw)/hr o f endotoxin; a dobutamine group, which received endotoxin and a continuous infusion of dobutamine (3 mug/kg bw/min); and a dopexamine group, which rec eived endotoxin and dopexamine (2 mug/kg bw/min). The experimental period w as 120 min. Measurements and Main Results: Mean arterial blood pressure (MAP), heart ra te (HR), and cardiac output (GO) were detected. Portal blood flow was measu red using an ultrasonic flow probe positioned around the portal vein, and s inusoidal blood flow was detected in the left liver lobe using intravital m icroscopy. Ail detected variables remained stable in the control group. In the endotoxin group, HR increased significantly and MAP decreased significa ntly from 111 +/- 10 mm Hg to 95 +/- 8 mm Hg at 120 mins, whereas GO remain ed unchanged. Both in the dobutamine and the dopexamine group HR increased and MAP decreased more than in the endotoxin group. GO increased in both gr oups significantly. Portal blood flow (23 +/- 4 mL/min to 16 +/- 3 mL/min) and sinusoidal blood flow (38.6 +/- 2.5 to 22.8 +/- 1.2 10(3) mum(3)/sec) d ecreased significantly in the endotoxin group. In the dobutamine and the do pexamine group portal and sinusoidal blood flow remained at baseline values . Conclusions: In our model of endotoxemia, dobutamine and dopexamine preserv ed systemic and hepatic blood flow. These preservations of hepatic blood fl ow during endotoxemia could portend beneficial effects but need to be studi ed further.