Observations of time-based measures of flow-mediated dilation of forearm conduit arteries: implications for the accurate assessment of endothelial fu…

2010

Endothelium-dependent flow-mediated dilation (FMD) is measured as the increase in diameter of a conduit artery in response to reactive hyperemia, assessed either at a fixed time point [usually 60-s post-cuff deflation (FMD60)] or as the maximal dilation during a 5-min continuous, ECG-gated, measurement (FMDmax-cont). Preliminary evidence suggests that the time between reactive hyperemia and peak dilation (time to FMDmax) may provide an additional index of endothelial health. We measured FMDmax-cont, FMD60, and time to FMDmax in 30 young healthy volunteers, 22 healthy middle-aged adults, 16 smokers, 23 patients with hypertension, 40 patients with coronary artery disease, and 22 patients wit…

Nitroglycerine causes mitochondrial reactive oxygen species production: In vitro mechanistic insights

2007

Background Nitroglycerine (GTN) is an organic nitrate that has been used for more than 100 years. Despite its widespread clinical use, several aspects of the pharmacology of GTN remain elusive. In a recent study, the authors of the present study showed that GTN causes opening of the mitochondrial permeability transition pore (mPTP) and mitochondrial production of reactive oxygen species (ROS). Objective In the present study, it was tested whether GTN-induced ROS production depends on mitochondrial potassium ATP-dependent channel or mPTP opening, and/or GTN biotransformation. Methods and results Isolated rat heart mitochondria were incubated with succinate (a substrate for complex II) and GT…

Tolerance to nitroglycerin-induced preconditioning of the endothelium: a human in vivo study

2009

Damage and dysfunction of the vascular endothelium critically influence clinical outcomes after ischemia and reperfusion (I/R). Brief exposure to organic nitrates can protect the vascular endothelium from I/R injury via a mechanism that is similar to ischemic preconditioning and is independent of hemodynamic changes. The clinical relevance of these protective effects clearly depends on whether they can be sustained over time. Twenty-four healthy (age 25–32) male volunteers were randomized to receive 1) transdermal nitroglycerin (GTN; 0.6 mg/h) administered for 2 h on 1 day only, 2) transdermal GTN for 2 h/day for 7 days, or 3) continuous therapy with transdermal GTN for 7 days. Eight volunt…

Pentaerythrityl Tetranitrate and Nitroglycerin, but not Isosorbide Mononitrate, Prevent Endothelial Dysfunction Induced by Ischemia and Reperfusion

2007

Background— Short term exposure to nitroglycerin (GTN) has protective properties that are similar to ischemic preconditioning. Whether other organic nitrates such as pentaerithrityl tetranitrate (PETN) and isosorbide mononitrate (ISMN) have similar protective effects has not been explored. Methods and Results— In a randomized, parallel, double blind, controlled trial, 37 healthy young volunteers received no therapy (n=10), transdermal GTN 1.2 mg for 2 hours (n=9), PETN 80 mg (n=9), or ISMN 40 mg (n=9). Twenty-four hours later, endothelium-dependent flow-mediated vasodilation (FMD) was measured before and after local exposure to ischemia and reperfusion (IR). In the no therapy group, IR blu…

Smoking-induced preconditioning: acute, but not chronic, smoking paradoxically protects the endothelium from ischemia and reperfusion

2013