[Roles of endogenous carbon monoxide in vasorelaxation disorder of femoral artery in diabetic rats].

Objective: To explore the effects of CO on femoral vasorelaxation in diabetic rats.

Methods: Using isolated vascular ring tension detecting technique, cumulative relaxation responses of femoral arteries to 10(-8) - 10(-4) mol/L acetylcholine (ACh) were measured. The content of COHb in blood was detected.

Results: Diabetic animals expressed lower weight [(249.38+/-7.58) g] than control rats [(345.83+/-12.14) g , P<0.01]. The blood sugar levels in diabetic rats [(20.28+/-0.35) mmol/L] were significantly higher than that in control rats [(5.56+/-0.19) mmol/L]. In addition,diabetic animals demonstrated elevated blood pressure [(118.75+/-8.33) mm Hg] after 4 weeks, (132.43+/-10.98) mm Hg after 8 weeks, (139.0+/-10.41) mm Hg after 12 weeks compared with control (108.43+/-4.18) mm Hg, P<0.01, 1 mm Hg=0.133 kPa] in a time-dependent manner. The COHb content in the blood was decreased in 4 weeks [(1.50%+/-0.21%) vs (2.50%+/-0.61%)], and restored to normal in 8 weeks and 12 weeks in diabetic rats. The dose cumulative vasorelaxation-response to ACh in diabetic rats was diminished (63.46%+/-2.48% after 4 weeks; 69.76%+/-7.61% after 8 weeks; 49.37%+/-4.74% after 12 weeks compared with control 96.81%+/-3.15%). Treatment with hemin did not affect weight, blood sugar and blood pressure in diabetic rats, markedly increased the COHb content in the blood (3.20%+/-0.73%, P<0.01) and improved the vasorelaxation disturbance of femoral arteries (69.76%+/-7.60%, P<0.01) in diabetic rats. While administration with ZnPP-IX could inhibit the production of COHb (0.93%+/-0.35%), and worse the hypertension [(130.84+/- 8.56) mm Hg] and aggravate the vasorelaxation disturbance (37.70%+/-5.65%) vs diabetes (63.46%+/-2.48%) in diabetic rats.

Conclusion: The results suggested that the decrease of blood CO in early stage of diabetic rats were related to the vasorelaxation disorder of femoral arteries, and that lead to hypertension in diabetic rats,which may be one of the important mechanisms of diabetes company hypertension.