Functional capacities of marsupial hearts: size and mitochondrial parameters indicate higher aerobic capabilities than generally seen in placental mammals

J Comp Physiol B. 2003 Sep;173(7):583-90. doi: 10.1007/s00360-003-0368-2. Epub 2003 Jul 25.

Abstract

This study of marsupial hearts explored the aerobic capacities of this group of mammals; recent information suggests that marsupials possess higher aerobic abilities than previously accepted. Characteristics such as heart mass, mitochondrial features and capillary parameters were examined. A comprehensive study of the heart of red kangaroos was included because of the high maximum oxygen consumption of this species. Goats were also included as a reference placental mammal. Marsupials have a heart that is generally larger than that of placentals. The allometric equation for the relationship between heart mass and body mass for marsupials was M(h)=7.5M(b)(0.944) (M(h) in g and M(b) in kg); the equivalent equation for placental mammals was M(h)=6.0M(b)(0.97). Mitochondrial volume density and inner mitochondrial surface density do not differ between the two mammal groups; although capillary parameters indicated a lower capillary volume in marsupials. Heart size appears to be the major difference between the two groups. The overall pattern seen in marsupials is similar to that of "athletic" placentals and indicates a relatively high aerobic potential.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Body Weight / physiology
  • Capillaries / physiology
  • Capillaries / ultrastructure
  • Goats / anatomy & histology
  • Goats / physiology
  • Heart / anatomy & histology
  • Heart / physiology*
  • Heart Atria / anatomy & histology
  • Heart Atria / ultrastructure
  • Heart Septum / physiology
  • Heart Septum / ultrastructure
  • Heart Ventricles / ultrastructure
  • Marsupialia / physiology*
  • Microscopy, Electron
  • Mitochondria, Heart / physiology*
  • Mitochondria, Heart / ultrastructure
  • Myocardium / cytology
  • Myocardium / ultrastructure
  • Organ Size / physiology
  • Ventricular Function