Hypoxia-induced changes in electrophysiological responses and associated calcium movements of flounder (Platichthys flesus) heart and gut.
1. Flounder hearts subjected to hypoxic conditions showed a reduction in contractile force. After 85 min in hypoxia-inducing salines, hearts were almost totally quiescent. 2. Membrane potentials were seen to change in hearts during hypoxic conditions. The action potential gradually declined in height but increased in duration and the resting membrane potential was also seen to decrease. 3. Sections of flounder gut, when subjected to identical hypoxic conditions as the hearts, showed no significant changes in either mechanical activity or membrane potential. 4. Heart and gut tissues were placed in hypoxia-inducing salines containing 45Ca either immediately or after a previous 3 hr exposure to hypoxia-inducing salines. Uptake of 45Ca increased beyond control values in both heart and gut subjected immediately to hypoxia. After 3 hr hypoxia exposure, uptake of 45Ca was reduced in heart but was not significantly different from controls in gut. 5. The changes seen in 45Ca uptake were far greater in heart tissue than in gut tissue. 6. In all physiological parameters examined, the gut tissue of the flounder is far more tolerant to hypoxic conditions than heart tissue.
Division of Biological Sciences, Lancaster University, Bailrigg, U.K.
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R
Lennard
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H
Huddart
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D005432:Flounder / Q000502:physiology*; D006321:Heart / Q000503:physiopathology*; D000860:Hypoxia / Q000503:physiopathology*; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000503:physiopathology; D008564:Membrane Potentials; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism*
D002118:Calcium