Naked Mole Rats Maintain Cardiovascular Function in Aging
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Naked mole rats live up to nine times longer than other similarly sized rodent species, and display little in the way of evident signs of aging across much of this span. Researchers, being thorough, are working their way through specific organs and systems of the body to see whether this holds generally for all of them - a part of the process of determining exactly why naked mole rats are so long-lived. Here the focus is the cardiovascular system:

The naked mole-rat (NMR) is the longest-lived rodent known, with a maximum lifespan potential (MLSP) of more than 31 years. Despite such extreme longevity, these animals display attenuation of many age-associated diseases and functional changes until the last quartile of their MLSP.

We questioned if such abilities would extend to cardiovascular function and structure in this species. To test this, we assessed cardiac functional reserve, ventricular morphology, and arterial stiffening in NMRs ranging from 2 to 24 years of age. Dobutamine echocardiography revealed no age-associated changes in left ventricular (LV) function either at baseline or with exercise-like stress. Baseline and dobutamine-induced LV pressure parameters also did not change. Thus the NMR, unlike other mammals, maintains cardiac reserve with age.

NMRs showed no cardiac hypertrophy, evidenced by no increase in cardiomyocyte cross-sectional area or LV dimensions with age. Age-associated arterial stiffening did not occur as there were no changes in aortic blood pressures or pulse-wave velocity. Only LV interstitial collagen deposition increased 2.5-fold from young to old NMRs. However, its effect on LV diastolic function is likely minor since NMRs experience attenuated age-related changes in diastolic dysfunction in comparison to other species.

Overall, these findings conform to the negligible senescence phenotype, as NMRs largely stave off cardiovascular changes for at least 75% of their MLSP. This suggests that using a comparative strategy to find factors that change with age in other mammals but not NMRs could provide novel targets to slow or prevent cardiovascular aging in humans.

Link: http://dx.doi.org/10.1152/ajpheart.00305.2014

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