This study was designed to investigate the effect of HOE 140 (a bradykinin β 2 receptor antagonist) and N w -nitro-l-arginine methyl-ester (L-NAME, a nitric oxide synthase inhibitor) on endothelial and β-cell function in induced streptozotocine (Stz) diabetic rats. The decrease in the insulinogenic index after Stz efffect (control 286.03 +/- 104.12 and Stz 18.22 +/- 10.77*, *P < 0.001 vs. Control) was partially prevented by L-NAME (46.54 +/- 10.12, P < 0.001) and HOE 140 (105.12 +/- 23.06, P < 0.001). It was observed in diabetic rats: L-NAME increased the pancreatic endothelin-1 (ET-1) production and HOE 140 did not. L-NAME and HOE 140 decreased the nitric oxide (NO) synthesis, increased prostacyclin 1-2 (PGI 2 ), and did not modify thromboxane A-2 (TxA 2 ). These results indicate that L-NAME and HOE 140 had a protective effect on the development of diabetes in the rat. The protective effect of L-NAME and HOE 140 on the insulinogenic index could be related to ET-1, bradykinin, PGI 2 , and NO.