Abstract:
Available evidence suggests that animals living in extreme cold are unusual in having a non-catecholamine based stress response, relying more on neural than hormonal control of the cardiovascular system. In situ heart preparations were used to measure a range of cardiovascular variables in Antarctic fish, including the effects of preload and after load, various vaso-active drugs (acetylcholine,
... adrenaline, noradrenalin, serotonin, carbachol and KCl as a control to determine maximum contractile response) and temperature. Parallel to this, the vasoconstrictor response of blood vessels was investigated by looking at isolated major arteries mounted in a myograph comparing the sensitivities to noradrenalin, carbachol and serotonin by means of the cumulative dose-response. Results for two Antarctic fish, Trematomus bernacchii and a truly pelagic Antarctic fish Dissostichus mawsoni were compared with similar data obtained from a temperate species Paranotothenia angustata to determine is this unusual pattern of agonist response evolved in response to low temperature or lifestyle. 
