Regular exercise improves cardiac contractile activation by modulating MHC isoforms and SERCA activity in orchidectomized rats.

Abstract

Data from the trial known as Testosterone in Older Men with Mobility Limitations (TOM) has indicated an association between testosterone administration and a greater risk for adverse cardiovascular events. We therefore propose that regular exercise is a cardioprotective alternative that prevents detrimental changes in contractile activation when a deficiency in male sex hormones exists. Ten-week-old orchidectomized (ORX) rats were subjected to a 9-wk treadmill running program at moderate intensity starting 1 wk after surgery. Although exercise-induced cardiac hypertrophy was observed both in rats that underwent ORX and sham surgery, regular exercise enhanced cardiac myofilament Ca(2+) sensitivity and myosin light-chain 2 phosphorylation only in rats that underwent a sham operation. Although the rats that had sham surgery and and given exercise exhibited no change in maximum developed tension, regular running prevented the suppression of maximum active tension in the hearts of ORX rats. Regular exercise also prevented a shift in myosin heavy chain (MHC) isoforms toward β-MHC, a reduction in sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) activity, and an increase in SERCA sensitivity in the hearts of ORX rats. Neither SERCA content nor its modulating component, phospholamban (PLB), was altered by exercise in either sham-operated or ORX rats. However, decreases in the phosphorylated Thr(17) form of PLB and the phosphorylated Thr(287) form of Ca(2+)/calmodulin-dependent kinase II in the hearts of ORX rats were abolished after regular exercise. These results thus support the use of regular running as a cardioprotective alternative to testosterone replacement in hypogonadal conditions.

• Authors: Pavarana Vutthasathien, Jonggonnee Wattanapermpool
• Journal: Journal of applied physiology (Bethesda, Md. : 1985) (J Appl Physiol (1985)) Vol. 119 Issue 7 Pg. 831-9 (Oct 01 2015) ISSN: 1522-1601 [Electronic] United States
• PMID: 26272317 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 the American Physiological Society.

Chemical References

• Calcium-Binding Proteins
• Myosin Light Chains
• myosin light chain 2
• phospholamban
• Calcium-Calmodulin-Dependent Protein Kinase Type 2
• Cardiac Myosins
• Sarcoplasmic Reticulum Calcium-Transporting ATPases
• Myosin Heavy Chains
• Calcium

Topics

• Animals
• Calcium (metabolism)
• Calcium-Binding Proteins (metabolism)
• Calcium-Calmodulin-Dependent Protein Kinase Type 2 (metabolism)
• Cardiac Myosins (metabolism)
• Male
• Myocardial Contraction (physiology)
• Myofibrils (metabolism)
• Myosin Heavy Chains (metabolism)
• Myosin Light Chains (metabolism)
• Orchiectomy
• Organ Size
• Phosphorylation
• Physical Conditioning, Animal (physiology)
• Rats
• Rats, Sprague-Dawley
• Running
• Sarcoplasmic Reticulum Calcium-Transporting ATPases (metabolism)