Premium
Effects of testosterone on cardiomyocyte calcium homeostasis and contractile function in female rats
Author(s) -
Beesley Ronald D.,
Palmer Bradley M.,
Casson Peter R.,
Toth Michael J.
Publication year - 2013
Publication title -
experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0958-0670
DOI - 10.1113/expphysiol.2012.067009
Subject(s) - homeostasis , testosterone (patch) , calcium , medicine , endocrinology , calcium metabolism , function (biology) , biology , microbiology and biotechnology
New Findings• What is the central question of this study? Androgen excess in women is associated with an elevated risk for heart disease. Whether some portion of this elevated risk is related to an effect of androgens on cariomyoctye function, however, has not been examined. To our knowledge, this is the first study to directly address the role of androgens in regulating cardiomyocyte contractile dynamics and calcium homeostasis. • What is the main finding and its importance? Our results suggest minimal acute or chronic effects of testosterone on cardiomyocyte shortening dynamics, calcium homeostasis or myosin heavy chain expression, suggesting that the detrimental effect of androgen excess on cardiovascular risk is not mediated through alterations in cardiomyocyte biology.The role of testosterone (T) in the regulation of cardiovascular function in females is not well understood. Our goal was to examine the effect of T on cardiomyocyte biology by measuring sarcomere shortening/relaxation and intracellular calcium cycling in adult female Sprague–Dawley rats. The rats were divided into the following four groups: (1) sham operated; (2) ovariectomized (OVX); (3) OVX plus T; and (4) OVX + T plus an aromatase inhibitor (AI). The final group was added to rule out effects from bioconversion of T to oestradiol. Sarcomere/calcium dynamics were measured after 4 weeks at 2 and 6 Hz, then at 6 Hz following exposure to 300 n m isoprenaline. Additionally, the acute (i.e. non‐genomic) effects of T were evaluated in sham‐operated and OVX + T + AI rats. There were no group differences, nor was there evidence for an effect of T on frequency or isoprenaline response. Additionally, there were no findings to indicate an acute, non‐genomic T effect. Moreover, the relative α‐ and β‐myosin heavy chain isoform complement was unchanged by OVX or T replacement. Our results argue against acute or chronic effects of T on cardiomyocyte shortening dynamics, calcium cycling or myosin heavy chain expression, arguing against any direct effect of T on cardiomyocyte function in adult females.