Cardiac function of the naked mole-rat: Ecophysiological responses to working underground

Kelly M. Grimes, Andrew Voorhees, Ying Ann Chiao, Hai Chao Han, Merry L. Lindsey, Rochelle Buffenstein

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The naked mole-rat (NMR) is a strictly subterranean rodent with a low resting metabolic rate. Nevertheless, it can greatly increase its metabolic activity to meet the high energetic demands associated with digging through compacted soils in its xeric natural habitat where food is patchily distributed. We hypothesized that the NMR heart would naturally have low basal function and exhibit a large cardiac reserve, thereby mirroring the species' low basal metabolism and large metabolic scope. Echocardiography showed that young (2-4 yr old) healthy NMRs have low fractional shortening (28 ± 2%), ejection fraction (43 ± 2%), and cardiac output (6.5 ± 0.4 ml/min), indicating low basal cardiac function. Histology revealed large NMR cardiomyocyte cross-sectional area (216 ± 10 μm2) and cardiac collagen deposition of 2.2 ± 0.4%. Neither of these histomorphometric traits was considered pathological, since biaxial tensile testing showed no increase in passive ventricular stiffness. NMR cardiomyocyte fibers showed a low degree of rotation, contributing to the observed low NMR cardiac contractility. Interestingly, when the exercise mimetic dobutamine (3 μg/g ip) was administered, NMRs showed pronounced increases in fractional shortening, ejection fraction, cardiac output, and stroke volume, indicating an increased cardiac reserve. The relatively low basal cardiac function and enhanced cardiac reserve of NMRs are likely to be ecophysiological adaptations to life in an energetically taxing environment.

Original languageEnglish (US)
Pages (from-to)H730-H737
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume306
Issue number5
DOIs
StatePublished - Mar 1 2014

Fingerprint

Mole Rats
Basal Metabolism
Cardiac Myocytes
Cardiac Output
Cardiac Volume
Dobutamine
Stroke Volume
Ecosystem
Echocardiography
Rodentia
Histology
Collagen
Soil
Food

Keywords

  • Cardiac reserve
  • Echocardiography
  • Ecophysiology
  • Left ventricular function
  • Naked mole-rat

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

Cardiac function of the naked mole-rat : Ecophysiological responses to working underground. / Grimes, Kelly M.; Voorhees, Andrew; Chiao, Ying Ann; Han, Hai Chao; Lindsey, Merry L.; Buffenstein, Rochelle.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 306, No. 5, 01.03.2014, p. H730-H737.

Research output: Contribution to journalArticle

Grimes, Kelly M. ; Voorhees, Andrew ; Chiao, Ying Ann ; Han, Hai Chao ; Lindsey, Merry L. ; Buffenstein, Rochelle. / Cardiac function of the naked mole-rat : Ecophysiological responses to working underground. In: American Journal of Physiology - Heart and Circulatory Physiology. 2014 ; Vol. 306, No. 5. pp. H730-H737.
@article{6e1574fbe6e545419427bd8a915d1237,
title = "Cardiac function of the naked mole-rat: Ecophysiological responses to working underground",
abstract = "The naked mole-rat (NMR) is a strictly subterranean rodent with a low resting metabolic rate. Nevertheless, it can greatly increase its metabolic activity to meet the high energetic demands associated with digging through compacted soils in its xeric natural habitat where food is patchily distributed. We hypothesized that the NMR heart would naturally have low basal function and exhibit a large cardiac reserve, thereby mirroring the species' low basal metabolism and large metabolic scope. Echocardiography showed that young (2-4 yr old) healthy NMRs have low fractional shortening (28 ± 2{\%}), ejection fraction (43 ± 2{\%}), and cardiac output (6.5 ± 0.4 ml/min), indicating low basal cardiac function. Histology revealed large NMR cardiomyocyte cross-sectional area (216 ± 10 μm2) and cardiac collagen deposition of 2.2 ± 0.4{\%}. Neither of these histomorphometric traits was considered pathological, since biaxial tensile testing showed no increase in passive ventricular stiffness. NMR cardiomyocyte fibers showed a low degree of rotation, contributing to the observed low NMR cardiac contractility. Interestingly, when the exercise mimetic dobutamine (3 μg/g ip) was administered, NMRs showed pronounced increases in fractional shortening, ejection fraction, cardiac output, and stroke volume, indicating an increased cardiac reserve. The relatively low basal cardiac function and enhanced cardiac reserve of NMRs are likely to be ecophysiological adaptations to life in an energetically taxing environment.",
keywords = "Cardiac reserve, Echocardiography, Ecophysiology, Left ventricular function, Naked mole-rat",
author = "Grimes, {Kelly M.} and Andrew Voorhees and Chiao, {Ying Ann} and Han, {Hai Chao} and Lindsey, {Merry L.} and Rochelle Buffenstein",
year = "2014",
month = "3",
day = "1",
doi = "10.1152/ajpheart.00831.2013",
language = "English (US)",
volume = "306",
pages = "H730--H737",
journal = "American Journal of Physiology - Renal Physiology",
issn = "0363-6127",
publisher = "American Physiological Society",
number = "5",

}

TY - JOUR

T1 - Cardiac function of the naked mole-rat

T2 - Ecophysiological responses to working underground

AU - Grimes, Kelly M.

AU - Voorhees, Andrew

AU - Chiao, Ying Ann

AU - Han, Hai Chao

AU - Lindsey, Merry L.

AU - Buffenstein, Rochelle

PY - 2014/3/1

Y1 - 2014/3/1

N2 - The naked mole-rat (NMR) is a strictly subterranean rodent with a low resting metabolic rate. Nevertheless, it can greatly increase its metabolic activity to meet the high energetic demands associated with digging through compacted soils in its xeric natural habitat where food is patchily distributed. We hypothesized that the NMR heart would naturally have low basal function and exhibit a large cardiac reserve, thereby mirroring the species' low basal metabolism and large metabolic scope. Echocardiography showed that young (2-4 yr old) healthy NMRs have low fractional shortening (28 ± 2%), ejection fraction (43 ± 2%), and cardiac output (6.5 ± 0.4 ml/min), indicating low basal cardiac function. Histology revealed large NMR cardiomyocyte cross-sectional area (216 ± 10 μm2) and cardiac collagen deposition of 2.2 ± 0.4%. Neither of these histomorphometric traits was considered pathological, since biaxial tensile testing showed no increase in passive ventricular stiffness. NMR cardiomyocyte fibers showed a low degree of rotation, contributing to the observed low NMR cardiac contractility. Interestingly, when the exercise mimetic dobutamine (3 μg/g ip) was administered, NMRs showed pronounced increases in fractional shortening, ejection fraction, cardiac output, and stroke volume, indicating an increased cardiac reserve. The relatively low basal cardiac function and enhanced cardiac reserve of NMRs are likely to be ecophysiological adaptations to life in an energetically taxing environment.

AB - The naked mole-rat (NMR) is a strictly subterranean rodent with a low resting metabolic rate. Nevertheless, it can greatly increase its metabolic activity to meet the high energetic demands associated with digging through compacted soils in its xeric natural habitat where food is patchily distributed. We hypothesized that the NMR heart would naturally have low basal function and exhibit a large cardiac reserve, thereby mirroring the species' low basal metabolism and large metabolic scope. Echocardiography showed that young (2-4 yr old) healthy NMRs have low fractional shortening (28 ± 2%), ejection fraction (43 ± 2%), and cardiac output (6.5 ± 0.4 ml/min), indicating low basal cardiac function. Histology revealed large NMR cardiomyocyte cross-sectional area (216 ± 10 μm2) and cardiac collagen deposition of 2.2 ± 0.4%. Neither of these histomorphometric traits was considered pathological, since biaxial tensile testing showed no increase in passive ventricular stiffness. NMR cardiomyocyte fibers showed a low degree of rotation, contributing to the observed low NMR cardiac contractility. Interestingly, when the exercise mimetic dobutamine (3 μg/g ip) was administered, NMRs showed pronounced increases in fractional shortening, ejection fraction, cardiac output, and stroke volume, indicating an increased cardiac reserve. The relatively low basal cardiac function and enhanced cardiac reserve of NMRs are likely to be ecophysiological adaptations to life in an energetically taxing environment.

KW - Cardiac reserve

KW - Echocardiography

KW - Ecophysiology

KW - Left ventricular function

KW - Naked mole-rat

UR - http://www.scopus.com/inward/record.url?scp=84899416709&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84899416709&partnerID=8YFLogxK

U2 - 10.1152/ajpheart.00831.2013

DO - 10.1152/ajpheart.00831.2013

M3 - Article

C2 - 24363308

AN - SCOPUS:84899416709

VL - 306

SP - H730-H737

JO - American Journal of Physiology - Renal Physiology

JF - American Journal of Physiology - Renal Physiology

SN - 0363-6127

IS - 5

ER -