Endocardial versus epicardial differences in L-type calcium current in canine ventricular myocytes studied by action potential voltage clamp

doi:10.1016/S0008-6363(02)00853-2

Cardiovascular Research 2003 58(1):66-75; doi:10.1016/S0008-6363(02)00853-2
© 2003 by European Society of Cardiology

This Article

	Full Text
	FREE Full Text (PDF)
	E-letters: Submit a response
	Alert me when this article is cited
	Alert me when E-letters are posted
	Alert me if a correction is posted

Services

	Email this article to a friend
	Similar articles in this journal
	Similar articles in PubMed
	Alert me to new issues of the journal
	Add to My Personal Archive
	Download to citation manager
	Request Permissions
	Disclaimer

Google Scholar

	Articles by Bányász, T.
	Articles by Nánási, P. P.
	Search for Related Content

PubMed

	PubMed Citation
	Articles by Bányász, T.
	Articles by Nánási, P. P.

Social Bookmarking

	What's this?

Endocardial versus epicardial differences in L-type calcium current in canine ventricular myocytes studied by action potential voltage clamp

Tamás Bányász^a, László Fülöp^a, János Magyar^a, Norbert Szentandrássy^a, András Varró^b and Péter P. Nánási^a^,*

^aDepartment of Physiology, University Medical School of Debrecen, P.O. Box 22, H-4012 Debrecen, Hungary
^bDepartment of Pharmacology and Pharmacotherapy, University of Szeged, P.O. Box 427, H-6701 Szeged, Hungary

^* Corresponding author. Tel.: +36-52-416-634; fax: +36-52-432-289. nanasi{at}phys.dote.hu

Objectives: The aim of the present study was to assess and comparethe dynamics of L-type Ca²⁺ current (I_Ca,L) during physiologicaction potential (AP) in canine ventricular cardiomyocytes ofepicardial (EPI) and endocardial (ENDO) origin. Methods: I_Ca,Lwas recorded on cells derived from the two regions of the heartusing both AP voltage clamp and conventional whole cell voltageclamp techniques. Results: AP voltage clamp experiments revealedthat the decay of I_Ca,L is monotonic during endocardial AP,whereas the current is double-peaked (displaying a second rise)during epicardial AP. The amplitude of the first peak was significantlygreater in ENDO (–4.6±0.8 pA/pF) than in EPI cells(–2.8±0.3 pA/pF). Application of epicardial APsas command pulses to endocardial cells yielded double-peakedI_Ca,L profiles, and increased the net charge entry carried byI_Ca,L during the AP from 0.187±0.059 to 0.262±0.056pC/pF (n = 5, P<0.05). No differences were observed in currentdensities and inactivation kinetics of I_Ca,L between EPI andENDO cells when studied under conventional voltage clamp conditions.Nisoldipine shortened action potentials and eliminated the domeof the epicardial AP. Conclusion: I_Ca,L was shown to partiallyinactivate before and deactivate during phase-1 repolarizationand reopening of these channels is responsible for the formationof the dome in canine EPI cells. The transmural differencesin the profile of I_Ca,L could be well explained with differencesin AP configuration.

KEYWORDS Ca-channel; Ion channels; Membrane currents; Membrane potential; Myocytes

Add to CiteULike CiteULike Add to Connotea Connotea Add to Del.icio.us Del.icio.us What's this?

This article has been cited by other articles:

S. G Campbell, S. N Flaim, C. H Leem, and A. D McCulloch
Mechanisms of transmurally varying myocyte electromechanics in an integrated computational model
Phil Trans R Soc A, September 28, 2008; 366(1879): 3361 - 3380.
[Abstract] [Full Text] [PDF]