Scaling of heart ventricle mass and body mass in the haemoglobinless Antarctic fish
Chionodraco hamatus
Lönnberg shows a relationship similar to those reported for other ‘cardiomegalic ’ icefish (
Chaenocephalus aceratus
and
Channichthys rhinoceratus
). An
in vitro
preparation of the heart of
C. hamatus
was set up to investigate the mechanical performance of this heart at different preloads and afterloads. It appears that this heart is well adapted to working within a range of preloads varying from —0.07 to —0.04 kPa, while it is unable to sustain increases of afterloads higher than 3.0 kPa. As in other teleosts, heart rate is unaffected by changes in preload and afterload. Increase in temperature from 0.5 to 5.8 °C affects heart rate whereas stroke volume is unaffected. On the whole, the
in vitro
data are similar to those
in vivo
measured in another icefish,
C. aceratus
and show that the heart of
C. hamatus
works as a typical volume pump. This is discussed in relation to both the structural constraints related to the cardiac design of this icefish and the biology of this unique vertebrate.
Genomic conservation of erythropoietic microRNAs (erythromiRs) in white-blooded Antarctic icefish
