Selective endothelin A (ETA) and combined ETA and ETB receptor antagonists are being investigated for use in treating diabetic nephropathy. However, the receptor-specific mechanisms responsible for producing the potential benefits have not been discerned. Thus, we determined the actions of ETA and ETB receptors on measures of glomerular function and renal inflammation in the early stages of diabetic renal injury in rats through the use of selective and combined antagonists. Six weeks after streptozotocin (STZ)-induced hyperglycemia, rats were given 2R-(4-methoxyphenyl)-4S-(1,3-benzodioxol-5-yl)-1-(N,N-di(n-butyl) aminocarbonyl-methyl)-pyrrolidine-3R-carboxylic acid (ABT-627) (5mg/kg/day), a selective ETA antagonist; (2R,3R,4S)-4-(benzo [d][1,3]dioxol-5-yl)-2- (3-fluoro-4-methoxyphenyl)-1-(2-(N-propylpentylsulfonamido) ethyl)pyrrolidine-3- carboxylic acid hydrochloride (A-182086) (10 mg/kg/day), a combined ET A/B antagonist; or vehicle for 1 week. Sham controls received STZ vehicle (saline). Hyperglycemia led to significant proteinuria, increased glomerular permeability to albumin (Palb), nephrinuria, and an increase in total matrix metalloprotease (MMP) and transforming growth factor-β1 (TGF-β1) activities in glomeruli. Plasma and glomerular soluble intercellular adhesion molecule-1 (sICAM-1) and monocyte chemoattractant protein-1 (MCP-1) were elevated after 7 weeks of hyperglycemia. Daily administration of both ABT-627 and A-182086 for 1 week significantly attenuated proteinuria, the increase in Palb, nephrinuria, and total MMP and TGF-β1 activity. However, glomerular sICAM-1 and MCP-1 expression was attenuated with ABT-627, but not A-182086, treatment. In summary, both selective ETA and combined ETA/B antagonists reduced proteinuria and glomerular permeability and restored glomerular filtration barrier component integrity, but only ETA-selective blockade had antiinflammatory and antifibrotic effects. We conclude that selective ETA antagonists are more likely to be preferred for the treatment of diabetic kidney disease. Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics.