|
| |
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
Journal of Experimental Biology, Vol 131, Issue 1 69-87, Copyright © 1987 by Company of Biologists
JOURNAL ARTICLES |
HO Portner
Institut fur Zoologie IV, Universitat Dusseldorf, FRG.
Proton balance is analysed in relation to the anaerobic and aerobic metabolism of carbohydrates, carbonic acids, amino acids and fat by considering oxidation, carboxylation, decarboxylation and phosphorylation reactions, as well as the influence of ammonium, on the acid-base status of animal tissues. The functional role of the adenylates, phosphagens and inorganic phosphate in acid-base balance is investigated with respect to differences in the physicochemical properties of organic and inorganic phosphates. General principles are established for different anaerobic metabolic pathways in species from several phyla. It is concluded that proton release from the substrate, which is always involved in substrate-level phosphorylations, is essential for the mechanism of ATP formation. Anaerobic metabolism, which is characterized by incomplete oxidation of carbon chains and an accumulation of acidic groups, supports pH regulation in facultative anaerobes by minimizing the amount of accumulated protons. High levels of phosphagens mean high proton absorption during hydrolysis and an increase in the intracellular buffer value. Decarboxylation reactions in catabolic pathways are equivalent to proton consumption. The degradation of carbonic acids during anaerobiosis, therefore, contributes to pH regulation. Release of ammonia or ammonium ions in catabolism is also linked to the buffering of protons originating from the formation of carboxyl groups and net cleavage of ATP. Net disposal of amino groups or ammonium ions by transamination, reductive amination or ion exchange does not change this general picture. The proton, bicarbonate and CO2 turnover in metabolic pathways is discussed with respect to the interrelationships between pH and metabolic regulation.
This article has been cited by other articles:
|
|
 |
|
  F. Melzner, C. Bock, and H.-O. Portner Critical temperatures in the cephalopod Sepia officinalis investigated using in vivo 31P NMR spectroscopy J. Exp. Biol., March 1, 2006; 209(5): 891 - 906. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. F. Burton Temperature and acid--base balance in ectothermic vertebrates: the imidazole alphastat hypotheses and beyond J. Exp. Biol., December 1, 2002; 205(23): 3587 - 3600. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Krumschnabel, C. Manzl, and P. J. Schwarzbaum Regulation of intracellular pH in anoxia-tolerant and anoxia-intolerant teleost hepatocytes J. Exp. Biol., March 13, 2002; 204(22): 3943 - 3951. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Portner, C Bock, and A Reipschlager Modulation of the cost of pHi regulation during metabolic depression: a (31)P-NMR study in invertebrate (Sipunculus nudus) isolated muscle J. Exp. Biol., January 8, 2000; 203(16): 2417 - 2428. [Abstract] [PDF]
|
|
|
|
 |
|
 V. J. T. van Ginneken, G. E. E. J. M. van den Thillart, H. J. Muller, S. van Deursen, M. Onderwater, J. Visee, V. Hopmans, G. van Vliet, and K. Nicolay Phosphorylation state of red and white muscle in tilapia during graded hypoxia: an in vivo 31P-NMR study Am J Physiol Regulatory Integrative Comp Physiol, November 1, 1999; 277(5): R1501 - R1512. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B Michaelidis, A Pallidou, and P Vakouftsi Effects of anoxia on the extra- and intracellular acid-base status in the land snail helix lucorum (L.): lack of evidence for a relationship between pyruvate kinase down-regulation and acid-base status J. Exp. Biol., January 6, 1999; 202(12): 1667 - 1675. [Abstract]
|
|
