Endothelial injury may contribute to the augmented coronary vascular tone seen in myocardial ischemia by impairing endothelial production or release of vasodilators. In vitro reactivity of arterial rings was studied after 60 min of coronary occlusion and 60 min of reperfusion in anesthetized dogs. Ischemia without reperfusion blunted contractile reactivity to potassium chloride (KCl), whereas ischemia plus reperfusion augmented contractile responses to both KCl and ergonovine. The response to acetylcholine, an endothelium-dependent vasodilator, was abolished in reperfused arteries, whereas the response to nitroprusside, an endothelium-independent vasodilator, was intact. Verapamil pretreatment restored KCl contractile responses to normal in reperfused coronary rings and partially restored endothelium-dependent relaxation. Electron microscopy revealed a nondenuding epicardial coronary endothelial injury in reperfused arteries. These data support the hypothesis that reperfusion of ischemic myocardium augments reactivity to vasoconstrictor agents by causing endothelial cell damage, excessive calcium influx, and loss of modulating vasodilator function.
K M VanBenthuysen, I F McMurtry, L D Horwitz
Usage data is cumulative from October 2023 through October 2024.
Usage | JCI | PMC |
---|---|---|
Text version | 237 | 0 |
53 | 31 | |
Figure | 0 | 6 |
Scanned page | 339 | 12 |
Citation downloads | 45 | 0 |
Totals | 674 | 49 |
Total Views | 723 |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.