Coronary alpha 1-adrenergic constrictor tone varies with intensity of exercise.
Coronary alpha 1-adrenergic constrictor tone varies with intensity of exercise.
复制标题
冠状动脉α1-肾上腺素能收缩肌张力随运动强度的变化而变化。
DOI：
10.1097/00005768-199601000-00015
复制
发表时间：
1996
影响因子：
4.1
通讯作者：
Gwirtz,PA
中科院分区：
文献类型：
--
作者：
Dodd-o,JM;Gwirtz,PA
本研究验证了一种假设，即α -肾上腺素能冠状动脉收缩张力随着运动强度的增加而增加，并在剧烈运动水平下对跨壁心肌血流量和收缩功能施加限制。9只狗长期测量左旋血流量（CBF）、整体心肌收缩功能（dP/dtmax）和局部心肌收缩功能（最大节段缩短率，dL/dtmax）。狗接受分级次最大运动测试，增加工作量，包括4.8公里/小时和6.4公里/小时，0、4、8、12和16%倾斜度。在不同的日子里，无论是载体（无菌水）或特异性α 1-肾上腺素能受体拮抗剂吡唑嗪（1微克）。公斤。Min-1)在运动时注入旋动脉。在三种最剧烈的运动水平下，去除α 1受体介导的冠状动脉收缩张力导致CBF分别比载药组增加15+/-7%、24+/-9%和35+/-10%。用标记微球测量另外4只狗的局部左心室血流量。在服用哌唑嗪后运动期间，心内膜和心外膜血流量平均增加16%，因此心内膜/心外膜血流量比没有改变。α - 1阻断后CBF的增强与局部和整体左心室收缩功能的显著增加有关。这些研究表明，均匀分布的跨壁冠状动脉α - 1收缩肌张力随着运动强度的增加而增加，因此对心肌功能施加了显著的限制。
This study tested the hypothesis that an alpha-adrenergic coronary constrictor tone increases with the intensity of exercise and imposes a limitation on transmural myocardial blood flow and contractile function during strenuous levels of exercise. Nine (9) dogs were chronically instrumented to measure left circumflex blood flow (CBF), global myocardial contractile function (dP/dtmax), and regional myocardial contractile function (maximal rate of segmental shortening, dL/dtmax). The dogs were subjected to a graded sub-maximal exercise test with increasing workloads encompassing 4.8 kph and 6.4 kph, 0, 4, 8, 12, and 16% incline. On separate days, either vehicle (sterile water) or the specific alpha 1-adrenergic receptor antagonist prazosin (1 microgram. kg-1. min-1) was infused into the circumflex artery during exercise. Removal of an alpha 1-receptor mediated coronary constrictor tone resulted in a 15+/-7%, 24+/-9%, and 35+/-10% greater increase in CBF compared with vehicle at the three most strenuous levels of exercise, respectively. Regional left ventricular blood flow was measured using labeled microspheres in four (4) additional dogs. Endocardial and epicardial blood flow increased equally by 16% during exercise after prazosin, such that the endocardial/epicardial flow ratio did not change. The augmentation in CBF after alpha 1-blockade was associated with significant increases in both regional and global left ventricular contractile function. These studies indicate that a uniformly distributed transmural coronary alpha 1-constrictor tone increases in magnitude with increasing levels of exercise intensity and, as a result, imposes a significant limitation on myocardial function.