Evaluation of coronary endothelial function by catheter-type NO sensor in high-fat-diet-induced obese dogs.

BACKGROUND

Direct measurement of plasma nitric oxide (NO) concentration is possible with a newly developed catheter-type sensor.

METHODS AND RESULTS

Adult mongrel dogs (n=5) were fed a high-fat diet (120 kcal . kg(-1) . day(-1)) for 8 months, then endothelial function was assessed by the change in NO concentration induced by acetylcholine (ACh) (DeltaNO). Simultaneously, average peak velocity (APV) was obtained by Doppler guide wire. Although fasting plasma glucose levels did not change after high-fat diet, fasting plasma insulin levels increased significantly (103+/-36 vs 106+/-27 mg/dl, P=0.89 and 0.15+/-0.15 vs 0.26+/-0.07 ng/ml, P=0.04, respectively). ACh-induced peak APV after high-fat feeding was not significantly different from that at baseline (ACh 0.1 microg/kg; 43+/-17 vs 51+/-7 cm/s, P=NS, ACh 0.4 microg/kg; 45+/-20 vs 47+/-16 cm/s, P=NS, respectively). The DeltaNO was significantly smaller after high-fat diet than at baseline (ACh 0.1 microg/kg; 2.6+/-1.6 vs 1.0+/-0.5 nmol/L, P=0.03, ACh 0.4 microg/kg; 3.8+/-2.3 vs 1.8+/-1.1 nmol/L, P=0.04, respectively).

CONCLUSIONS

In high-fat-diet-induced obese dogs NO production was impaired in the early stage when the coronary flow response to ACh may be preserved.