Abstract

Increased ambient O₂ tension (hyperoxia, P0₂ = 500 Torr) was employed to generate a respiratory acidosis in the hemolymph of P. leniusculus in order to analyse subsequent mechanisms of acid-base compensation. Crayfish were able to completely restore circulating pH within 24 h by accumulating metabolic bicarbonate (HC0₃) at fixed CO₂ tension. During this time a net branchial excretion of acidic equivalents was measured, which was correlated with a more negative Cl- balance. Changes in net Na+ movement were due to changes in the exchange diffusion component (Na+/Na+) and were not associated with H+ or NH₄ exchange. There was however a good correlation between Cl- outflux and Hco3 uptake suggesting that HCO3- is accumulated in the hemolymph by reversal of the branchial Cl-/HCO₃- exchanger. Collection of urine revealed that the antennal gland was also involved in acid-base regulation duririg hyperoxia since titratable acidity and ammonia excretion increased. Clearance ratio analysis failed to reveal any changes in postfiltrational electrolyte reprocessing mechanisms.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: