Skip Navigation

Cardiovascular Research 2000 47(4):769-777; doi:10.1016/S0008-6363(00)00147-4
© 2000 by European Society of Cardiology
This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow E-letters: Submit a response
Right arrow Alert me when this article is cited
Right arrow Alert me when E-letters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Egdell, R. M.
Right arrow Articles by Macleod, K. T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Egdell, R. M.
Right arrow Articles by Macleod, K. T.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Copyright © 2000, European Society of Cardiology

Relative importance of SR load and cytoplasmic calcium concentration in the genesis of aftercontractions in cardiac myocytes

Robin M. Egdell*, Ayesha I. De Souza and Kenneth T. Macleod

Cardiac Medicine, Imperial College School of Medicine, National Heart and Lung Institute, Dovehouse Street, London SW3 6LY, UK

* Corresponding author. Tel.: +44-171-352-8121; fax: +44-171-351-8145 r.egdell{at}hotmail.com

Objective: To determine whether calcium overload of the sarcoplasmic reticulum underlies drive train-induced aftercontractions in cardiac myocytes. Methods: Sarcoplasmic reticulum calcium contents were measured immediately prior to drive train-induced aftercontractions in isolated guinea pig cardiac myocytes, using caffeine application under voltage clamp conditions. Cell shortening during caffeine exposure and cell shortening during the final stimulated beat of the drive train and the delay between caffeine exposure and the onset of inward current were also used as indirect measures of sarcoplasmic reticulum load. Results: At the threshold for aftercontractions, all four measures of sarcoplasmic reticulum load showed interruption of the positive relationship between stimulation frequency and sarcoplasmic reticulum content, the sarcoplasmic reticulum being no more loaded prior to an aftercontraction than following subthreshold drive trains. Intracellular calcium concentration, estimated with the calcium-sensitive dye indo-1, was higher in cells showing aftercontractions than those not. Conclusions: We conclude that calcium overload of the sarcoplasmic reticulum does not underlie spontaneous calcium release in this situation and the primary trigger for spontaneous release may instead be raised cytoplasmic calcium concentration.

KEYWORDS Arrhythmia (mechanisms); Calcium (cellular); e–c coupling; Myocytes; SR (function)


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




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.