Reversal by L-arginine of a dysfunctional arginine/nitric oxide pathway in the endothelium of the genetic diabetic BB rat

Summary We examined the effects of acute supplementation with arginine in vitro on endothelium-dependent relaxation in aortic rings taken from female genetic, diabetes-prone BB rats. Sensitivity to norepinephrine-induced contraction was unaltered in rings of diabetic BB rats compared to rings from non-diabetic littermates. In precontracted rings, acetylcholine produced a concentration-dependent relaxation which was impaired by diabetes. This relaxation was blocked by l-nitroarginine in both control and diabetic rings. Addition of 3 mmol/l l-arginine (but not d-arginine) enhanced relaxation in diabetic rings similar to that seen in control rings without arginine. l-arginine had no effect on acetylcholine-induced relaxation in control rings. In contrast, relaxation-induced by nitroglycerin in diabetic rings without endothelium was not altered by l-arginine treatment. Thus, a defect in the utilization of arginine by nitric oxide synthase exists in the endothelium of the diabetic BB rat. [Diabetologia (1997) 40: 910–915] Received: 24 February 1997 and in revised form: 17 April 1997