title: Blood acid-base changes during experimental emersion and reimmersion of the intertidal crab Carcinus maenas (L.).
abstract: The time course of blood acid-base changes was studied in Carcinus maenas during experimental emersion and reimmersion at 15 degrees C by measuring pH and PCO2 and calculating bicarbonate concentration. During the first 4 hr of the emersion period, a marked rise of PCO2 entails a respiratory acidosis which is progressively compensated by a slow increase of the bicarbonate concentration; this compensation is completed after about 100 hr and the steady state mean pH value approximates that found for the immersed controls. Return to aquatic conditions is characterized by a rapid decrease of both PCO2 and blood bicarbonate concentration. During the first 2 hr of the reimmersion period, the decrease of blood bicarbonate concentration is accompanied by excretion of a significant amount of base in water, thus suggesting that readjustments of acid-base balance take place at least in part by ionic exchanges between the blood and the external milieu. Initial status was restored after 9 hr. These finding agree with the general views concerning the blood acid-base changes which must occur at transition from water-to air-breathing.
mesh_terms: D000136:Acid-Base Equilibrium; D000818:Animals; D001639:Bicarbonates / Q000097:blood; D001769:Blood; D003386:Brachyura / Q000502:physiology*; D002245:Carbon Dioxide / Q000097:blood; D006863:Hydrogen-Ion Concentration; D007101:Immersion; D010313:Partial Pressure; D012119:Respiration; D012623:Seawater; D013997:Time Factors
chemical_list: D001639:Bicarbonates; D002245:Carbon Dioxide