Blood acid-base buffering: Explanation of the effectiveness of bicarbonateand citrate ingestion

Robergs, Robert A. (2002) Blood acid-base buffering: Explanation of the effectiveness of bicarbonateand citrate ingestion. Journal of Exercise Physiology Online, 5(3), pp. 1-5.

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There exists confusion in the exercise and sports science community over the function and capacity of the bicarbonate (HCO3- buffer system, as well as the mechanism of action of citrate ingestion for raising blood bicarbonate and pH. This commentary provides a brief explanation of buffers, and their mechanism of action. Blood buffers must function between a pH range of 7.2 to 7.4, while muscle intracellular buffers must function between pH values of 6.2 to 7.0. Ideally, the pK' characteristics of a buffer must be close to the pH of the tissue. However, the pK' values for (carbonic acid (H2CO3) and HCO3 are 3.77 and 10.2, respectively. Despite these values, the bicarbonate system is a good blood buffer for pH values close to 7.4. This pK' and pH disparity results from the influence of body CO2 stores on each of H2CO3 and HCO3, effectively altering the pK' of the system close to 7.4. Increasing blood HCO3- increases the buffering capacity of blood, which in turn can improve intense intermittent exercise performance. Citrate does not have a pK' of an ionizable group that is effective within the range of blood pH. Nevertheless, citrate ingestion can increase blood HCO3- and pH. A review of the metabolic fate of citrate reveals that no protons are consumed in citrate catabolism. Thus, the benefit of citrate to blood buffering is based on its minor buffering capacity throughout the range of blood pH, and electrochemical properties that effectively raise blood HCO3- and pH though adjustments to the distributions of charged molecules within the intracellular and extracellular spaces. More research is needed for establishing the optimal mix of bicarbonate and citrate that most effectively improves blood proton buffering and intense exercise performance.

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ID Code: 96877
Item Type: Review
Refereed: Yes
Keywords: acetic acid; bicarbonate; buffer; carbonic acid; citric acid, bicarbonate blood level; blood pH; chemical structure; electrochemical analysis; exercise; pH measurement; review
ISSN: 1097-9751
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Current > Schools > School of Exercise & Nutrition Sciences
Copyright Owner: Copyright 2002 American Society of Exercise Physiologists
Deposited On: 04 Aug 2016 02:08
Last Modified: 04 Aug 2016 02:08

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