Concentration-response curves to sodium nitroprusside (SNP; A) and propylamine propylamine NONOate (PAPA NONOate; B) in uterine arteries from nonpregnant and pregnant control [Wistar (W)] and diabetic (GK) rats. SNP-induced relaxation was reduced in GK-nonpregnant (NP; n = 9) rats compared with W-NP (n = 9) rats and in W-NP and GK-pregnant (Preg; n = 9) compared with W-Preg (n = 7). PAPA NONOate-induced relaxation was increased in GK-NP (n = 8) compared with W-NP (n = 9) and GK-Preg (n = 9) rats and in GK-Preg compared with W-Preg (n = 7) rats, and was reduced in W-Preg compared with W-NP rats. Values are means ± SE. aP < 0.05, GK-NP vs. W-NP; bP < 0.05, W-NP vs. W-Preg; cP < 0.05, GK-Preg vs. W-Preg; dP < 0.05, GK-NP vs. GK-Preg.