Background: The present study aimed to elucidate the effect of long-term treatment with nitroglycerin (NTG) on the bioavailability of nitric oxide (NO) examined by a catheter-type NO sensor. The study also examined whether these effects could be modified by an antioxidant, an angiotensin converting enzyme inhibitor, or an angiotensin II type 1 receptor antagonist (ARB).
Methods and results: Male New Zealand rabbits were treated for 7 days with NTG patches, either alone or in combination with tempol, enalapril, or valsartan (ARB). The plasma NO concentration was measured with the catheter-type NO sensor. The plasma peroxynitrite concentration was measured by enzyme-linked immunosorbent assay. An increase in plasma NO concentration in response to acetylcholine (ACh) were significantly attenuated in the NTG-treated group as compared with the control. Plasma peroxynitrite concentration in NTG-treated group was significantly higher as compared with the control. The negative effects of NTG were significantly suppressed by the co-treatment with tempol, enalapril or valsartan.
Conclusions: Chronic treatment of rabbits with NTG elicits the impairment of the ACh-stimulated NO production. In addition, the negative effects of NTG might be prevented by the co-treatment with drugs attenuating nitrosative stress.