Fifteen anesthetised pigs (25-30 kg) were divided into three equal groups, sham, dopexamine (D) (10 micrograms/kg/min), and placebo (P). Sepsis was induced by fecal peritonitis in the D and P groups and colloid was infused to try to maintain mean arterial blood pressure (MABP) at a constant value and the hemodynamics measured at baseline and hourly for 8 hr. There was an initial increase in MABP and systemic vascular resistance (SVR) in the P group but not the dopexamine (D) group. Cardiac output (CO) in the P group showed a small decline but increased in the D group. The portal blood flow (PVF) in the P group fell with MABP but increased in the D group as MABP fell. The sham group showed normal ultrastructure and cellular integrity. Occlusion of the hepatic sinusoids was similar in the D and P groups. There was a greater area of Kupffer cells and endothelial cells in the P group, suggesting a greater inflammatory reaction than was found in the D group. Ultrastructure and mitochondrial integrity was better maintained in the D group. Dopexamine hydrochloride infusion maintained CO, increased PVF, and attenuated hepatic ultrastructural changes compared to placebo in a porcine fecal peritonitis model of multisystem organ failure.