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This Article Full Text Full Text (PDF) All Versions of this Article: 107/2/593    most recent 91218.2008v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map 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 Google Scholar Articles by Prímola-Gomes, T. N. Articles by Natali, A. J. PubMed PubMed Citation Articles by Prímola-Gomes, T. N. Articles by Natali, A. J.

Exercise capacity is related to calcium transients in ventricular cardiomyocytes

¹Department of Physiology and Biophysics, ²Department of Biochemistry and Immunology, Biological Sciences Institute, and ³Department of Physical Education, Physical Education, Physiotherapy, and Occupational Therapy School, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais; and ⁴Department of Physical Education, Biological Sciences and Health Center, Federal University of Viçosa, Viçosa, Minas Gerais, Brazil

Submitted 10 September 2008 ; accepted in final form 28 May 2009

The aim of the present study was to evaluate the Ca²⁺ handling and contractility properties of cardiomyocytes isolated from rats with high intrinsic aerobic exercise capacity. Standard-performance (SP) and high-performance (HP) rats were categorized with a treadmill progressive exercise test according to the exercise time to fatigue (TTF). The SP group included rats with TTF between 16.63 and 46.57 min, and the HP group included rats with TTF >46.57 min. Isolated ventricular cardiomyocytes were dissociated from the hearts of SP and HP rats, and intracellular global Ca²⁺ ([Ca²⁺]_i) transients were measured. The [Ca²⁺]_i transient peak was increased in the HP group relative to the SP group (5.54 ± 0.31 vs. 4.18 ± 0.12 F/F₀; P 0.05) and was positively correlated with the TTF attained during the progressive test (r = 0.81). We also performed contractility measurements in isolated cardiomyocytes and found higher amplitude of contraction in the HP group compared with the SP group (6.7 ± 0.2 vs. 6.0 ± 0.3% resting cell length; P 0.05). To reinforce the intrinsic differences between SP and HP rats, we performed Western blot experiments and observed increased expression of sarco(endo)plasmic reticulum Ca²⁺-ATPase type 2a (1.30 ± 0.07 vs. 1.74 ± 0.18 arbitrary units; P 0.05) and ryanodine receptor type 2 (1.86 ± 0.13 vs. 3.57 ± 0.12 arbitrary units; P 0.05) in HP rats. In summary, our data showed important intrinsic differences in cardiomyocyte properties that could explain some of the divergence observed in rats with high intrinsic aerobic exercise capacity.

intrinsic exercise aerobic capacity; confocal microscopy