Abstract 1140: Chronic Exercise Protects against Macro- and Micro- vascular Endothelial Dysfunction Induced by Acute Hypertension during Exertion
Introduction: Exercise is recommended to reduce cardiovascular disease risk. However, exercise-induced hypertension may threaten vascular endothelial health. Previous studies indicate conditioned subjects (EX) are protected from endothelial dysfunction observed in sedentary (SED) subjects after weight lifting (WL).
Hypothesis: We hypothesized that:
Exercise induced hypertension impairs endothelial function in the microcirculation; and
Chronic exercise protects against macro- and micro- vascular endothelial dysfunction induced by WL.
Methods: Healthy, lean sedentary subjects, and EX (runners >15 miles/week or WL >3×/week), underwent blood pressure measurements during a single progressive leg press WL session reaching 85% 1 repetition maximum. Brachial artery flow- mediated vasodilation (FMD) and nitroglycerin (NTG; 0.4 mg) dilations were determined with ultrasonography. Microvascular specimens were obtained with gluteal subcutaneous fat pad biopsies. Isolated microvessels from the same subjects were cannulated for vascular reactivity measurements to acetylcholine (ACh; 10−9–10−4 M) pre and post WL. Separately, superoxide production was assessed with hydroethidine fluorescence.
Results: All subjects were normotensive and the blood pressure responses to WL were similar (max SBP: 177 ± 5 mmHg). Baseline FMD tended to be lower in EX (6.7 ± 1.1%; n=12) vs. SED (8.8 ± 1.6%; n=14; p=0.2). Acute WL reduced FMD in SED (−3.5 ± 1.2%; p=0.004) but not in EX (+1.6 ± 0.7%; p=0.002 vs. SED). NTG responses were similar between groups. Dilation to ACh was significantly reduced post WL in SED subjects but not EX. Superoxide production was increased in microvessels from SED subjects post WL (fluorescence ratio: 2.4 ± 0.6 vs. baseline p=0.03; n=7). The superoxide scavenger Tiron restored the dilator response to ACh in SED and reduced superoxide fluorescence in microvessels post WL (fluorescence ratio: 0.78 ± 0.06 vs. baseline; p=0.03; n=4). In conclusion, these data indicate chronic exercise protects against microvascular endothelial dysfunction after exertion. Reactive oxygen species in the microcirculation may play a role in endothelial dysfunction after exposure to exercise-induced hypertension.