system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, RESULTS. Meshes: Animals, Disease Models, Animal, Drug Administration Schedule, Endothelium, Insulin Resistance, Male, Oxidative Stress, Phosphodiesterase Inhibitors, Piperazines, Purines, Rats, Rats, Wistar, Sildenafil Citrate, Sulfones.
user
Does daily treatment with sildenafil reverse endothelial dysfunction and oxidative stress in an animal model of insulin resistance? Context: Patients with insulin resistance exhibit endothelial dysfunction with decreased nitric oxide (NO) production and increased oxidative stress. We postulated that daily sildenafil improved endothelial function in fructose-fed rats. Wistar rats were fed a standard or fructose-enriched diet (FFR) for 9 wk. From weeks 6-8, sildenafil was administered twice daily (sc, 20 m g/kg), followed by a 1-wk washout. Concentration-response curves (CRCs) to endothelium-dependent (acetylcholine [Ach] and A23187) and -independent (sodium nitroprusside [SNP]) relaxing agents were performed on isolated precontracted aortas and superior mesenteric arteries (SMAs). Vascular cyclic guanosine monophosphate (cGMP) content, urinary excretion of nitrates/nitrites (NOx) and 8-isoprostanes (IPT), and plasma levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were evaluated. Relaxations to ACh were significantly reduced in aortas and SMAs of FFR. Sildenafil restored ACh-induced relaxations in aortas and provoked a significant leftward shift of the CRC to ACh in SMAs, whereas it did not modify the enhanced relaxations to SNP in FFR. IL-6, TNF-alpha, vascular cGMP, and urinary NOx levels were not modified by the fructose or sildenafil treatment. Urinary IPT levels were significantly elevated in FFR and normalized by sildenafil.
assistant
Endothelial dysfunction and oxidative stress associated with insulin resistance can be reversed by daily sildenafil, even 1 wk after treatment cessation. Final Decision: yes