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This Article Full Text Full Text (PDF) All Versions of this Article: 579/2/465    most recent jphysiol.2006.127480v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Rosati, B. Articles by McKinnon, D. Search for Related Content PubMed PubMed Citation Articles by Rosati, B. Articles by McKinnon, D. Related Collections Cardiovascular

¹ Department of Physiology and Biophysics
² Institute of Molecular Cardiology
³ Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, USA
⁴ Department of Pharmacology, Columbia University, New York, NY, USA

This study examines the molecular basis for the T-type and L-type Ca²⁺ currents in canine Purkinje cells. The I_CaT in Purkinje cells was completely suppressed by 200 nM kurtoxin, a specific blocker of both Ca_v3.1 and Ca_v3.2 channels. Since only Ca_v3.2 mRNA is expressed at high levels in Purkinje fibres, being approximately 100-fold more abundant than either Ca_v3.1 or Ca_v3.3 mRNAs, it is concluded that the Ca_v3.2 gene encodes the bulk of the T-type Ca²⁺ channels in canine Purkinje cells. This conclusion is consistent with the sensitivity of the current to blockade by Ni²⁺ ions (K_D = 32 µM). For L-type channels, Ca_v1.2 mRNA was most abundant in Purkinje fibres but a significant level of Ca_v1.3 mRNA expression was also found. A comparison of the sensitivity to blockade by isradipine of the L-type currents in Purkinje cells and ventricular epicardial myocytes, which only express Ca_v1.2, suggests that the Ca_v1.3 channels make, at most, a minor contribution to the L-type current in canine Purkinje cells.

(Received 27 December 2006; accepted after revision 9 January 2007; first published online 11 January 2007)
Corresponding author B. Rosati: Department of Physiology and Biophysics, BST Room 124, Level 6, Stony Brook University, Stony Brook, NY 11794-8661, USA. Email: brosati{at}notes.cc.sunysb.edu

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