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Basic Res Cardiol (2011) 106:10091022 DOI 10.1007/s00395-011-0218-4
ORIGINAL CONTRIBUTION
K201 (JTV-519) alters the spatiotemporal properties of diastolic Ca2+ release and the associated diastolic contraction during b-adrenergic stimulation in rat ventricular cardiomyocytes
E. B. Elliott H. Hasumi N. Otani
T. Matsuda R. Matsuda N. Kaneko
G. L. Smith Christopher M. Loughrey
Received: 6 April 2011 / Revised: 24 July 2011 / Accepted: 20 August 2011 / Published online: 8 September 2011 The Author(s) 2011. This article is published with open access at Springerlink.com
Abstract K201 has previously been shown to reduce diastolic contractions in vivo during b-adrenergic stimulation and elevated extracellular calcium concentration ([Ca2?]o). The present study characterised the effect of
K201 on electrically stimulated and spontaneous diastolic sarcoplasmic reticulum (SR)-mediated Ca2? release and contractile events in isolated rat cardiomyocytes during b-adrenergic stimulation and elevated [Ca2?]o. Parallel experiments using confocal microscopy examined spontaneous diastolic Ca2? release events at an enhanced spatiotemporal resolution. 1.0 lmol/L K201 in the presence of 150 nmol/L isoproterenol (ISO) and 4.75 mmol/L [Ca2?]o
signicantly decreased the amplitude of diastolic
contractions to *16% of control levels. The stimulated free Ca2? transient amplitude was signicantly reduced, but stimulated cell shortening was not signicantly altered. When intracellular buffering was taken into account, K201 led to an increase in action potential-induced SR Ca2?
release. Myolament sensitivity to Ca2? was not changed by K201. Confocal microscopy revealed diastolic events composed of multiple Ca2? waves (23) originating at various points along the cardiomyocyte length during each diastolic period. 1.0 lmol/L K201 signicantly reduced the(a) frequency of diastolic events and (b) initiation points/ diastolic interval in the remaining diastolic events to 61% and 71% of control levels respectively. 1.0 lmol/L K201 can reduce the probability of spontaneous diastolic Ca2?
release and their associated contractions which may limit the propensity for the contractile dysfunction observed in vivo.
Keywords Calcium K201 JTV-519
Sarcoplasmic reticulum Calcium waves
Abbreviations[Ca2?]i Intracellular calcium concentration [Ca2?]o Extracellular calcium concentration DAD Delayed after depolarisationsDD Diastolic dysfunctionF/F0 Quiescent uorescence
ICa L-type Ca2? currentKH KrebsHenseleit solution
NCX Sodiumcalcium exchangerNE Nor-epinephrineRCL Resting cell lengthRyR2 Ryanodine receptorSERCA Sarcoplasmic/endoplasmic Ca2? ATPase pump SR Sarcoplasmic reticulum
Electronic supplementary material The online version of this article (doi:http://dx.doi.org/10.1007/s00395-011-0218-4
Web End =10.1007/s00395-011-0218-4 ) contains supplementary material, which is available to authorized users.
E. B. Elliott G....