HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 89/4/407    most recent expphysiol.2004.027482v1 Alert me when this article is cited 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 Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Goldspink, D. F. Articles by Tan, L.-B. Search for Related Content PubMed PubMed Citation Articles by Goldspink, D. F. Articles by Tan, L.-B. Related Collections Muscle

¹ The Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, 15–21 Webster Street, Liverpool L3 2ET, UK² Michael Reese Hospital and Medical Center, 2929 S Ellis, Chicago, IL 60616-3990, USA³ Academic Unit of Molecular and Vascular Medicine, Martin Wing, Leeds General Infirmary, Leeds LS2 9JT, UK

High levels of catecholamines are myotoxic but the relative amounts of apoptosis and necrosis have not been established in vivo in cardiac and skeletal muscles. Immunohistochemistry was used to detect and quantify myocyte-specific necrosis (myosin antibody in vivo) and apoptosis (caspase-3 antibody in vitro) in the heart and soleus muscles of male Wistar rats that had received single subcutaneous injections of isoprenaline over the range 1 µg to 5 mg [kg body weight (BW)]^–1. Peak myocyte apoptosis occurred 3–6 h after, and necrosis 18 h after, a single injection of 5 mg (kg BW)^–1 isoprenaline in vivo. In the heart myocyte death was mediated through the ß₁-adrenergic receptor whereas myocyte death in the soleus muscle was mediated through the ß₂-adrenergic receptor. Cardiomyocyte death was heterogeneously distributed throughout the heart, being greatest in the left ventricle (LV) subendocardium and peaking close to the apex, but with significantly more necrosis than apoptosis. Extensive co-localization of caspase-3 and myosin labelling was found in the myocytes of both the heart and the slow-twitch soleus muscle. This, together with similar spatial distributions and responses to catecholamine doses, suggests that either caspase-3 activation occurs in necrotic as well as apoptotic myocytes or that a large proportion of apoptotic myocytes progress to secondary necrosis in vivo.

(Received 18 February 2004; accepted after revision 20 April 2004; first published online 6 May 2004)
Corresponding author D. F Goldspink: The Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, 15–21 Webster Street, Liverpool L3 2ET, UK. Email: D.Goldspink{at}livjm.ac.uk