Physiological response to emersion in the amphibious crab Chasmagnathus granulata (Decapoda Grapsidae): Biochemical and ventilatory adaptations.

LUQUET, C; CERVINO, C; ANSALDO, M; CARRERA PV; KOCMUR, S; DEZI, R.

COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR AND INTEGRATIVE PHYSIOLOGY

Elsevier

Lugar: Amsterdam; Año: 1998 vol. 121 p. 385 - 393

1095-6433

The adaptation of Chasmagnathus granulata to air breathing depends on two types of physiological mechanisms: (1) Biochemical adjustments, comprising the achievement of new steady state values for partial pressure of carbon dioxide (PCO2Chasmagnathus granulata to air breathing depends on two types of physiological mechanisms: (1) Biochemical adjustments, comprising the achievement of new steady state values for partial pressure of carbon dioxide (PCO2PCO2 ) and total carbon dioxide concentration (CCO2CCO2 ). The initial increase in hemolymph bicarbonate is stabilized by dehydration to CO22 presumably catalyzed by carbonic anhydrase (CA) at the basolateral side of the gill epithelium. Thus, an adequate transbranchial gradient of PCO2PCO2 is restored. Inhibition of CA with acetazolamide (Az) reduces the rate of CO2 excretion and elevates PCO22 excretion and elevates PCO2 . The respiratory acidosis caused by increased PCO2PCO2 is compensated by increase in the difference between Na and Cl concentrations. Az does not affect hemolymph ionic concentrations. (2) Ventilatory control: untreated animals show a significant decrease in scaphognathite frequency (FSC) during emersion, while Az treated crabs show a slight increase of this variable. FSC of Az crabs tends to decrease with hemolymphatic CO2, presumably by clearance of the CA inhibitor from hemolymph. These results suggest that C. granulata possess a ventilatory control based on a primary oxygen-dependent stimulus and a secondary one dependent on CO2. © 1998 Elsevier Science Inc. All rights reserved. and Cl concentrations. Az does not affect hemolymph ionic concentrations. (2) Ventilatory control: untreated animals show a significant decrease in scaphognathite frequency (FSC) during emersion, while Az treated crabs show a slight increase of this variable. FSC of Az crabs tends to decrease with hemolymphatic CO2, presumably by clearance of the CA inhibitor from hemolymph. These results suggest that C. granulata possess a ventilatory control based on a primary oxygen-dependent stimulus and a secondary one dependent on CO2. © 1998 Elsevier Science Inc. All rights reserved.FSC) during emersion, while Az treated crabs show a slight increase of this variable. FSC of Az crabs tends to decrease with hemolymphatic CO2, presumably by clearance of the CA inhibitor from hemolymph. These results suggest that C. granulata possess a ventilatory control based on a primary oxygen-dependent stimulus and a secondary one dependent on CO2. © 1998 Elsevier Science Inc. All rights reserved.2, presumably by clearance of the CA inhibitor from hemolymph. These results suggest that C. granulata possess a ventilatory control based on a primary oxygen-dependent stimulus and a secondary one dependent on CO2. © 1998 Elsevier Science Inc. All rights reserved.C. granulata possess a ventilatory control based on a primary oxygen-dependent stimulus and a secondary one dependent on CO2. © 1998 Elsevier Science Inc. All rights reserved.2. © 1998 Elsevier Science Inc. All rights reserved. Keywords : Acid–base balance; Crabs; Heart frequency; Ion regulation; Respiration; Ventilatory frequency: Acid–base balance; Crabs; Heart frequency; Ion regulation; Respiration; Ventilatory frequency