Agonist specific L-type Ca(2+)-current stimulation in ventricular myocytes by a novel steroid-like compound

Keller, Markus; Pignier, Christophe; Santelli, Maurice; Vacher, Bernard; Niggli, Ernst; Egger, Marcel (2006). Agonist specific L-type Ca(2+)-current stimulation in ventricular myocytes by a novel steroid-like compound. Cell calcium, 39(5), pp. 425-33. Amsterdam: Elsevier 10.1016/j.ceca.2006.01.006

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In cardiac muscle the amplitude of Ca(2+) transients can be increased by enhancing Ca(2+) influx. Among the processes leading to increased Ca(2+) influx, agonists of the L-type Ca(2+)-channel can play an important role. Known pharmacological Ca(2+)-channel agonists act on different binding sites on the channel protein, which may lead not only to enhanced peak currents, but also to distinct changes in other biophysical characteristics of the current. In this study, membrane currents were recorded with the patch-clamp technique in the whole-cell configuration in guinea pig isolated ventricular myocytes in combination with confocal fluorescence Ca(2+) imaging techniques and a variety of pharmacological tools. Testing a new positive inotropic steroid-like compound, we found that it increased the L-type Ca(2+)-current by 2.5-fold by shifting the voltage-dependence of activation by 20.2 mV towards negative potentials. The dose-response relationship revealed two vastly different affinities (EC(50(high-affinity))=4.5+/-1.7 nM, EC(50(low-affinity))=8.0+/-1.1 microM) exhibiting differential pharmacological interactions with three classes of Ca(2+)-current antagonists, suggesting more than one binding site on the channel protein. Therefore, we identified and characterized a novel positive inotropic compound (F90927) as a member of a new class of Ca(2+)-channel agonists exhibiting unique features, which set it apart from other presently known L-type Ca(2+)-channel agonists.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Physiology
UniBE Contributor:	Keller, Markus, Niggli, Ernst, Egger, Marcel
ISSN:	0143-4160
ISBN:	16540165
Publisher:	Elsevier
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:45
Last Modified:	05 Dec 2022 14:13
Publisher DOI:	10.1016/j.ceca.2006.01.006
PubMed ID:	16540165
Web of Science ID:	000236998700005
URI:	https://boris.unibe.ch/id/eprint/18502 (FactScience: 665)