Interest in comparative acid-base physiology has considerably grown
during last decades even in the absence of major technical or conceptual
advances. This is firstly because it has become clear that the
extracellular acid-base state reflects the performance of many exchange
functions at the organism level: respiration and ventilation of the gas
exchange surfaces, metab- olism, iono-and osmoregulation. Such functions
are much in- fluenced by ambient conditions, and the measurement of
acid- base parameters thus provides useful information about the
organism's responses to environmental challenges. Secondly, many
processes at the molecular level are now known to be pH- sensitive, and
acid-base regulation thus appears to be a major requirement for the
functional integrity of cells and organisms. How extracellular acid-base
balance can be maintained in a wide variety of animals living in
different conditions is the sub- ject of this book. The approach is
comparative and environ- mental throughout. All body fluids share
similar buffer proper- ties, and common physicochemical principles apply
to any acid- base system. However, in accord with differing designs and
con- straints along animal evolution, varying effector organs and
mechanisms are at work to maintain an appropriate acid-base state in the
organism. Particular emphasis is placed on the fun- damental differences
between water and air breathers and on the acid-base and respiratory
problems arising at the transition from an aquatic to a terrestrial
life. Also the complex array of factors influencing the acid-base state
in water-dwelling animals is thoroughly discussed.