To evaluate the effects of bilateral ureteral obstruction (BUO) on the levels of G-protein subunits in glomeruli, we examined the types and amounts of G-protein subunits in glomerular membranes from sham-operated control (SOC) rats and rats with BUO of 24 hours duration utilizing bacterial toxin-catalyzed ADP-ribosylation and specific antibodies. ADP-ribosylation catalyzed by cholera or pertussis toxin demonstrated the presence of Gs and Gi proteins in glomerular membranes. Immunoblots further revealed the existence of two types of Gαs (45 and 52 kDa), as well as Gαi2 (40 kDa), Gαi3 (41 kDa), Gαq/11 (42 kDa) and Gβ (35 to 36 kDa) in glomerular membranes. The predominant subspecies of Gαs was the 52 kDa protein. Detectable amounts of Gαo were not found in glomerular membranes. Moreover, G-protein subunits were not detected in cytosolic extracts of glomeruli. Both forms of Gαs and Gαq/11 were significantly reduced in glomerular membranes from rats with BUO when compared to SOC rats. No significant difference in total Gαi, Gαi2 and Gαi3 and Gβ content was observed between the two groups of rats. In vivo pretreatment of rats with simultaneous administration of the angiotensin-converting enzyme inhibitor, enalaprilat, and the thromboxane synthase inhibitor, OKY-046, maintained the amount of Gαs and Gαq/11 in rats with BUO at the levels seen in SOC rats. The two drugs did not affect the amounts of G-protein subunits in glomerular membranes of SOC rats. We conclude that the decreased mass of two forms of Gαs and Gαq/11 in glomerular membranes from rats with BUO of 24 hours duration is caused by elevated levels of angiotensin II, thromboxane A2, or both, that occur as a consequence of obstruction. This decrease in Gαs and Gαq/11 content may contribute in part to the changes in glomerular function present at 24 hours after the onset of bilateral ureteral obstruction.