High inborn aerobic capacity does not protect the heart following myocardial infarction

Hoydal, M.A., Kaurstad, G., Rolim, N.P., Johnsen, A.B., Alves, M., Koch, L.G., Britton, S.L., Stolen, T.O., Smith, G.L. and Wisloff, U. (2013) High inborn aerobic capacity does not protect the heart following myocardial infarction. Journal of Applied Physiology, 115(12), pp. 1788-1795. (doi:10.1152/japplphysiol.00312.2013)

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Abstract

Maximal oxygen uptake (V̇O2max) is a strong prognostic marker for morbidity and mortality, but the cardio-protective effect of high inborn V̇O2max remains unresolved. We aimed to investigate whether rats with high inborn V̇O2max yield cardio-protection after myocardial infarction (MI) compared with rats with low inborn V̇O2max. Rats breed for high capacity of running (HCR) or low capacity of running (LCR) were randomized into HCR-SH (sham), HCR-MI, LCR-SH, and LCR-MI. V̇O2max was lower in HCR-MI and LCR-MI compared with respective sham (P < 0.01), supported by a loss in global cardiac function, assessed by echocardiography. Fura 2-AM loaded cardiomyocyte experiments revealed that HCR-MI and LCR-MI decreased cardiomyocyte shortening (39%, and 34% reduction, respectively, both P < 0.01), lowered Ca2+ transient amplitude (37%, P < 0.01, and 20% reduction, respectively), and reduced sarcoplasmic reticulum (SR) Ca2+ content (both; 20%, P < 0.01) compared with respective sham. Diastolic Ca2+ cycling was impaired in HCR-MI and LCR-MI evidenced by prolonged time to 50% Ca2+ decay that was partly explained by the 47% (P <0.01) and 44% (P < 0.05) decrease in SR Ca2+-ATPase Ca2+ removal, respectively. SR Ca2+ leak increased by 177% in HCR-MI (P < 0.01) and 67% in LCR-MI (P < 0.01), which was abolished by inhibition of Ca2+/calmodulin-dependent protein kinase II. This study demonstrates that the effect of MI in HCR rats was similar or even more pronounced on cardiac- and cardiomyocyte contractile function, as well as on Ca2+ handling properties compared with observations in LCR. Thus our data do not support a cardio-protective effect of higher inborn aerobic capacity.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Smith, Professor Godfrey
Authors: Hoydal, M.A., Kaurstad, G., Rolim, N.P., Johnsen, A.B., Alves, M., Koch, L.G., Britton, S.L., Stolen, T.O., Smith, G.L., and Wisloff, U.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
Journal Name:Journal of Applied Physiology
ISSN:8750-7587
ISSN (Online):1522-1601

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