Effect of renal ischemia reperfusion injury on renal function. Serum creatinine of WT (n = 6), low-TF (n = 6), and WT (n = 6) mice treated with hirudin and PAR-1^−/− (n = 6) mice undergoing 25 minutes of bilateral renal ischemia. Treatment was followed by (A) 5 or (B) 24 hours of reperfusion or, for WT mice, sham surgery. IR resulted in significant renal failure in WT versus sham-operated mice. *P < .001 at both 5 and 24 hours of reperfusion. Low-TF, hirudin-treated WT mice and PAR-1^−/− mice developed significantly less severe renal failure compared with WT mice (**P < .001). (C) Serum creatinine of PAR-2^−/− (n = 8) or background strain control WT (PAR-2^+/+) (n = 8) mice undergoing 25 minutes of bilateral renal ischemia followed by 24 hours of reperfusion. PAR-2^−/− mice developed similar degree of renal failure compared with the WT controls. Data are expressed as mean ± SEM.