Early studies on reptiles demonstrated that plasma pH increases as body temperature falls (Robin, 1962). Rahn (1967) proposed that plasma pH in all poikilothermic vertebrates is regulated as body temperature changes so as to maintain a constant relative alkalinity, i.e. a constant [OH-]/[H+] ratio, and Reeves (1972) suggested a way in which this could be achieved. Known as the ‘imidazole alphastat hypothesis’, it postulates that PCO2 is regulated (by way of ventilation) so that the fractional dissociation (alpha) of the imidazole moiety of histidine is kept constant. As the pK' of imidazole changes with temperature in about the same manner as the neutral pH of water (Heisler, 1986), the alphastat hypothesis is consistent with that of constant relative alkalinity.
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JOURNAL ARTICLE| 01 April 1993
THE RELATIONSHIP BETWEEN INTRACELLULAR pH AND SEASONAL TEMPERATURE IN THE BROWN TROUT SALMO TRUTTA
P. J. Butler
Online Issn: 1477-9145
Print Issn: 0022-0949
© 1993 by Company of Biologists
J Exp Biol (1993) 177 (1): 293–297.
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P. J. Butler, N. Day; THE RELATIONSHIP BETWEEN INTRACELLULAR pH AND SEASONAL TEMPERATURE IN THE BROWN TROUT SALMO TRUTTA. J Exp Biol 1 April 1993; 177 (1): 293–297. doi: https://doi.org/10.1242/jeb.177.1.293
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