Usage Information
Citation Information: J Clin Invest. 1980;65(1):161-171. https://doi.org/10.1172/JCI109647.
Abstract
Alpha compared to beta adrenergic contributions to dysrhythmias induced by left anterior descending coronary occlusion and by reperfusion were assessed in chloralose-anesthetized cats (n = 96). Alpha receptor blockade with either phentolamine or prazosin significantly reduced the number of premature ventricular complexes during coronary reperfusion (321 +/- 62-14 +/- 10 premature ventricular complexes, P less than 0.001), abolished early ventricular fibrillation (from 25% in controls to 0%), and prevented the increase in idioventricular rate seen with coronary reperfusion. However, beta-receptor blockade was without effect. Ventricular dysrhythmias induced by coronary occlusion alone (without reperfusion) were attenuated markedly by alpha-receptor blockade under conditions in which perfusion (measured with radiolabeled microspheres) within ischemic zones was not affected. Alternative sympatholytic interventions including pretreatment with 6-hydroxydopamine to deplete myocardial norepinephrine from 8.8 +/- 1.4 to 0.83 +/- 0.2 ng/mg protein and render the heart unresponsive to tyramine (120 microgram/kg) attenuated dysrhythmias induced by both coronary occlusion and reperfusion in a fashion identical to that seen with alpha-receptor blockade. Although efferent sympathetic activation induced by left stellate nerve stimulation increased idioventricular rate from 66 +/- 6 to 144+/- 7 beats/min (P less than 0.01) before coronary occlusion, this response was blocked by propranolol but not by phentolamine. In contrast, during reperfusion the increase in idioventricular rate induced by left stellate nerve stimulation (to 203 +/- 14) was not inhibited by propranolol but was abolished by phentolamine (79 +/- 10). Intracoronary methoxamine (0.1 microM) in animals depleted of myocardial catecholamines by 6-hydroxydopamine pretreatment did not affect idioventricular rate before coronary occlusion. However, early after coronary reperfusion, methoxamine increased idioventricular rate from 33 +/- 7 to 123 +/- 21 beats/min (P less than 0.01). Thus, enhanced alpha-adrenergic responsiveness occurs during myocardial ischemia and appears to be primary mediator of the electrophysiological derangements and resulting malignant dysrhythmias induced by catecholamines during myocardial ischemia and reperfusion.
Authors
D J Sheridan, P A Penkoske, B E Sobel, P B Corr
Usage data is cumulative from November 2023 through November 2024.
| Usage | JCI | PMC |
|---|---|---|
| Text version | 116 | 0 |
| 67 | 24 | |
| Scanned page | 392 | 4 |
| Citation downloads | 46 | 0 |
| Totals | 621 | 28 |
| Total Views | 649 | |
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.
Copyright © 2024 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)