Mechanisms of the compensation of blood respiratory acid‐base disturbances in the shore crab, Carcinus maenas (L.)

Abstract

AbstractApparent exchange of base with the external water was measured in crabs under various experimental conditions where compensation of blood respiratory acid‐base disturbances is known to occur. Crabs reimmersed after a long emersion time, or returned to normal conditions after hyperoxic or hypercapnic exposure, or loaded with sodium bicarbonate, apparently excrete a significant amount of an unidentified base to the external water. Conversely, an apparent acid output occurs during the first hours of an hyperoxic or hypercapnic treatment. As demonstrated by significant changes of the titration alkalinity of the respired water, the site of these exchange processes appears to be mainly the gills. Antennal gland excretion seems of minor importance as shown by obstructing the urinary pores or measuring urine acid‐base parameters. It is also inferred that exchange mechanisms between the cells and the extracellular fluid are also involved in the compensation of blood respiratory acidbase disturbances.