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 portal 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 groups: a control group, which only received Ringer's solution; an endotoxin group, which received a continuous infusion of 2 mg/kg body weight (bw)/hr of endotoxin; a dobutamine group, which received endotoxin and a continuous infusion of dobutamine (3 mug/kg bw/min); and a dopexamine group, which received endotoxin and dopexamine (2 mug/kg bw/min). The experimental period was 120 min. Measurements and Main Results: Mean arterial blood pressure (MAP), heart rate (HR), and cardiac output (GO) were detected. Portal blood flow was measured using an ultrasonic flow probe positioned around the portal vein, and sinusoidal blood flow was detected in the left liver lobe using intravital microscopy. Ail detected variables remained stable in the control group. In the endotoxin group, HR increased significantly and MAP decreased significantly from 111 +/- 10 mm Hg to 95 +/- 8 mm Hg at 120 mins, whereas GO remained unchanged. Both in the dobutamine and the dopexamine group HR increased and MAP decreased more than in the endotoxin group. GO increased in both groups 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) decreased significantly in the endotoxin group. In the dobutamine and the dopexamine group portal and sinusoidal blood flow remained at baseline values. Conclusions: In our model of endotoxemia, dobutamine and dopexamine preserved systemic and hepatic blood flow. These preservations of hepatic blood flow during endotoxemia could portend beneficial effects but need to be studied further.