Shepherd John R A, Joyner Michael J, Dinenno Frank A, Curry Timothy B, Ranadive Sushant M
Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota; and.
Department of Health and Exercise Science, and Center for Cardiovascular Research, Colorado State University, Fort Collins, Colorado.
J Appl Physiol (1985). 2016 Sep 1;121(3):629-35. doi: 10.1152/japplphysiol.01034.2015. Epub 2016 Jul 21.
In humans, intra-arterial ATP infusion in limbs mimics many features of exercise hyperemia. However, it remains unknown whether ATP can evoke the prolonged vasodilation seen during exercise. Therefore, we addressed two questions during a continuous 3-h brachial artery infusion of ATP [20 μg·100 ml forearm volume (FAV)(-1)·min(-1)]: 1) would skeletal muscle blood flow remain robust or wane over time (tachyphylaxis); and 2) would the hyperemic response to moderate-intensity exercise performed during the ATP administration be blunted compared with that during control (saline) infusion. Nine participants (25 ± 1 yr) performed one trial consisting of seven bouts of rhythmic handgrip exercise (20 contractions/min at 20% of maximum), two bouts during saline (control), and five bouts during 180 min of continuous ATP infusion. Five minutes of ATP infusion resulted in a 710% increase in forearm vascular conductance (FVC) from control (4.8 ± 0.77 vs. 35.0 ± 5.7 ml·min(-1)·100 mmHg(-1)·dl FAV(-1), P < 0.05). Contrary to our expectations, FVC did not wane over time with values of 35.0 ± 5.7 and 36.0 ± 7.7 ml·min(-1)·100 mmHg(-1)·dl FAV(-1) (P > 0.05), seen prior to the exercise bouts at 5 vs. 150 min, respectively. During superimposed exercise, FVC increased from 35.0 ± 5.7 to 49.6 ± 5.4 ml·min(-1)·100 mmHg(-1)·dl FAV(-1) at 5 min and 36.0 ± 7.7 to 54.5 ± 5.0 at 150 min (P < 0.05). Our findings demonstrate ATP vasodilation is prolonged over time without tachyphylaxis; however, exercise hyperemia responses remain intact. Our results challenge the metabolic theory of exercise hyperemia, suggesting a disconnect between matching of blood flow and metabolic demand.
在人体中，肢体动脉内输注ATP可模拟运动性充血的许多特征。然而，ATP是否能诱发运动期间出现的持续性血管舒张仍不清楚。因此，我们在持续3小时的肱动脉输注ATP [20 μg·100 ml前臂容积（FAV）⁻¹·min⁻¹]过程中解决了两个问题：1）骨骼肌血流量会随时间保持强劲还是减弱（快速耐受性）；2）与对照（生理盐水）输注期间相比，在ATP给药期间进行的中等强度运动的充血反应是否会减弱。九名参与者（25±1岁）进行了一项试验，包括七组有节奏的握力运动（每分钟20次收缩，为最大收缩力的20%），两组在生理盐水（对照）输注期间进行，五组在持续180分钟的ATP输注期间进行。输注ATP 5分钟后，前臂血管传导率（FVC）较对照增加了710%（4.8±0.77 vs. 35.0±5.7 ml·min⁻¹·100 mmHg⁻¹·dl FAV⁻¹，P<0.05）。与我们的预期相反，FVC并未随时间减弱，在运动组前5分钟和150分钟时分别为35.0±5.7和36.0±7.7 ml·min⁻¹·100 mmHg⁻¹·dl FAV⁻¹（P>0.05）。在叠加运动期间，FVC在5分钟时从35.0±5.7增加到49.6±5.4 ml·min⁻¹·100 mmHg⁻¹·dl FAV⁻¹，在150分钟时从36.0±7.7增加到54.5±5.0（P<0.05）。我们的研究结果表明，ATP血管舒张作用随时间延长且无快速耐受性；然而，运动性充血反应仍然完好。我们的结果对运动性充血的代谢理论提出了挑战，表明血流量与代谢需求的匹配之间存在脱节。
