Fig. 4

Sex difference in the severity of acute kidney injury after cardiac arrest and cardiopulmonary resuscitation (CA/CPR) and the effect of post-arrest administration of 17β-estradiol. Blood and tissue samples were collected 24 h after CA/CPR in young (10–15 weeks) male or female mice intravenously injected with 10 μg of 17β-estradiol or vehicle 15 min after return of spontaneous circulation. There was a sex difference in estrogen-mediated amelioration of renal injury following CA/CPR in young mice. Estradiol treatment significantly reduced serum urea nitrogen (a), serum creatinine (b), and tubular cell death (c) in males (triangle), but young females were not affected, because injury was small (circle). Data are presented as mean ± standard deviation, n = 14 or 15 per group, *P < 0.05 by two-way analysis of variance with post hoc Sidak’s test. EST 17β-estradiol-treated mice, VEH vehicle-treated mice