Niche expansion of the shorthorn sculpin (Myoxocephalus scorpius) to Arctic waters is supported by a thermal independence of cardiac performance at low temperature

• Cardiovascular adaptations that permit successful exploitation of polar marine waters by fish requires a capacity to negate or compensate for the depressive effects of low temperatures on physiological processes. Here, we examined the effects of acute and chronic temperature change on the maximum cardiac performance of shorthorn sculpin (Myoxocephalus scorpius (L., 1758)) captured above the Arctic Circle. Our aim was to establish if the sculpin's success at low temperatures was achieved through thermal independence of cardiac function or via thermal compensation as a result of acclimation. Maximum cardiac performance was assessed at both 1 and 6 degrees C with a working perfused heart preparation that was obtained after fish had been acclimated to either 1 or 6 degrees C. Thus, tests were performed at the fish's acclimation temperature and with an acute temperature change. Maximum cardiac output, which was relatively large (> 50 mL.min(-1).kg(-1) body mass) for a benthic fish at a frigid temperature, was found to be independent of both acclimation temperature and test temperature. While maximum beta-adrenergic stimulation produced positive chronotropy at both acclimation temperatures, inotropic effects were weak or absent. We conclude that thermal independence of cardiac performance at low temperature likely facilitated the exploitation of polar waters by the shorthorn sculpin.

Ämnesord

NATURVETENSKAP  -- Biologi -- Zoologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Zoology (hsv//eng)

Nyckelord

Myoxocephalus scorpius

perfused heart

cardiac output

adrenaline

power generation

pressure

TROUT ONCORHYNCHUS-MYKISS

COD GADUS-MORHUA

FLOUNDER

PLEURONECTES-AMERICANUS

RAINBOW-TROUT

WINTER FLOUNDER

SALMO-GAIRDNERI

CARDIOVASCULAR-RESPONSES

ADRENERGIC SENSITIVITY

DIFFERENT ENVIRONMENTS

EXTRACELLULAR CALCIUM

LLIGAN CL

1989

JOURNAL OF FISH BIOLOGY

V35

P229

Myoxocephalus scorpius

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