IMPROVEMENT OF RENAL HEMODYNAMICS IN ENDOTOXIN SHOCK WITH DOPAMINE, PHENOXYBENZAMINE AND DEXTRAN

¹ Veterans Administration Hospital and Departments of Physiology and Biophysics, Medicine, and Surgery, University of Oklahoma Medical Center, Oklahoma City, Oklahoma

The effects of dopamine were evaluated on the renal hemodynamics of dogs in endotoxin shock. In control animals receiving endotoxin only, mean systemic arterial pressure decreased to 60%, renal blood flow decreased to 51%, renal resistance increased to 116%, glomerular filtration rate decreased to 9% and urine flow decreased to 18% of control values. Pre- and post-treatment of shocked animals with dopamine showed no significant improvements in any of the measured parameters. Post-treatment with a combination of phenoxybenzamine (1 mg/kg), dextran (20 nil/kg) and dopamine (mean infusion rate of 38 µg/kg/min) significantly changed the measured parameters in endotoxin-injected animals. In this group, mean systemic arterial pressure was 65%, renal blood flow was 128%, renal resistance was 47%, glomerular filtration rate was 29% and urine flow was 117% of control values at the termination of the dopamine infusion. Thirty minutes after termination of the dopamine infusion, mean systemic arterial pressure was 59%, renal blood flow was 69%, renal resistance was 76%, glomerular filtration rate was 19% and urine flow was 44% of control values. These findings show that dopamine significantly improves renal hemodynamics in endotoxin shock only when phenoxybenzamine is given to block the constrictor action of dopamine and when dextran is administered for volume replacement concomitantly with dopamine infusion.