Mechanism of renal vasoconstriction with thromboxane mimetic: engagement of tubuloglomerular feedback.

U-46,619 infused at 10 ng.kg-1.min-1 in anesthetized rats reduced the glomerular capillary pressure only during engagement of tubuloglomerular feedback (TGF). 100 ng.kg-1.min-1 induced renal vasoconstriction, whereas femoral vasoconstriction and a rise in BP required 1,000-10,000 ng.kg-1.min-1. These results implicate TGF in the extreme sensitivity of the kidney to TxA2/PG endoperoxide receptor activation.