Usage Information
Citation Information: J Clin Invest. 1987;80(1):88-94. https://doi.org/10.1172/JCI113068.
Abstract
The hyperthyroid state is associated with increased myocardial contractility. To clarify responsible mechanisms, we examined the effects of thyroid hormone on slow Ca channels, beta-adrenergic receptors, transsarcolemmal 45Ca flux and cytosolic free calcium in cultured chick ventricular cells. Compared with cells grown without triiodothyronine (T3), cells grown in 10 nM T3 possessed 67% (P less than 0.05) more dihydropyridine 3H-PN200-110 binding sites, 24% (P less than 0.05) more beta-adrenergic antagonist 3H-CGP12177 binding sites, a 57% (P less than 0.05) greater nifedipine-sensitive initial 45Ca uptake rate, and a 31% (P less than 0.05) greater nifedipine-sensitive 45Ca uptake rate in response to BAY k 8644. Time-averaged mean intracellular free Ca concentration ([Ca]i) measured with fura-2, total protein content, and dissociation constant values for 3H-PN200-110 or 3H-CGP12177 binding was not significantly different in the two groups of cells. BAY k 8644 (1 microM) increased mean [Ca]i 2.85- or 2.16-fold in cells grown with or without 10 nM T3, respectively. l-Isoproterenol (1 microM) increased [Ca]i 1.53- or 1.28-fold in cells grown with or without 10 nM T3, respectively. We conclude that thyroid hormone augments transsarcolemmal Ca influx, at least in part via slow Ca channels associated with increased numbers of these channels. T3-treated cells appear to be more responsive to the effects of BAY k 8644 or isoproterenol on [Ca]i.
Authors
D Kim, T W Smith, J D Marsh
Usage data is cumulative from February 2024 through February 2025.
| Usage | JCI | PMC |
|---|---|---|
| Text version | 177 | 5 |
| 88 | 18 | |
| Scanned page | 280 | 15 |
| Citation downloads | 59 | 0 |
| Totals | 604 | 38 |
| Total Views | 642 | |
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 © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)