everal clinical and basic studies have shown that chronic treatment with nitroglycerin (NTG) causes endothelial dysfunction. [1][2][3] However, the limitation of these data is that the release of nitric oxide (NO) from the endothelium was estimated on the basis of the comparison of vessel relaxation. We have very recently shown that longterm treatment of New Zealand White rabbits with NTG decreases basal, as well as acetylcholine (ACh)-induced plasma NO concentrations by using a catheter-type NO sensor, accompanied with augmentation of nitrosative stress. 4 In addition, we have shown that the negative effects of NTG could be prevented by co-treatment with drugs attenuating nitrosative stress, such as, angiotensin-converting enzyme inhibitors and angiotensin II type 1 receptor blockers (ARB). 4 The peroxisome proliferator-activated receptor (PPAR) is a nuclear receptor that has recently emerged as a pivotal intracellular controller of systemic and vascular processes, including inflammation and atherosclerosis. 5 PPAR is expressed in all major cell types involved in the initiation and evolution of the atherosclerotic plaque, including endothelial cells, vascular smooth muscle cells, macrophages, and T lymphocytes, where it might exert anti-inflammatory and potentially anti-atherogenic effects. 6 Interestingly, PPAR stimulation improves insulin resistance as well as endothelial function in patients with type 2 diabetes. 7 However, it is unknown whether this beneficial effect of PPAR stimulation on endothelial function could extend to NTG-induced endothelial dysfunction. It is clinically important because patients with diabetes mellitus have frequently accompanied with ischemic heart disease.By using the catheter-type NO sensor we investigated to clarify the effect of PPAR agonist on the impairment of bioavailability of NO induced by chronic treatment with NTG patches. The present study has shown that the NTGinduced impairment of NO bioavailability is significantly reversed by the co-treatment with a PPAR agonist, pioglitazone.
Methods
A Catheter Type NO SensorIntegrated architecture and performance of the cathetertype NO sensor have been described previously. [8][9][10] In brief, an NO sensor (amino-700 XL, Innovative Instruments, 700 m in diameter at the detection tip) was mounted in a 4-Fr catheter (1,200 mm long; Hirakawa Hewtech, Tokyo, Japan) and fixed with silicon adhesive. The oxidative current of NO was monitored by with an NO monitor (model inNO-T, Innovative Instruments). Each sensor was calibrated by using an NO-saturated pure water as previously described. [8][9][10] Briefly, NO-saturated pure water was prepared by bubbling pure NO gas in oxygen-free pure water. Using a gas-tight syrindge, 5 l was injected into a well Background We examined whether nitroglycerin (NTG)-induced impairment of nitric oxide (NO) bioavailability could be modified by a peroxisome proliferator-activated receptor (PPAR) agonist.
Methods and ResultsMale New Zealand White rabbits were treated for 7 days with NTG patches, either al...