Faculty of Science

Permanent URI for this community

http://hdl.handle.net/1993/36346

Browse

Browsing Faculty of Science by Subject "Acid-base regulation"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Open Access
    THE MECHANISM OF ACID-BASE REGULATION IN SEAWATER-ACCLIMATED GREEN CRABS, CARCINUS MAENAS
    (Canadian Journal of Zoology, 2015) Fehsenfeld, Sandra; Weihrauch, Dirk
    The present study investigated acid-base regulatory mechanisms in seawater-acclimated green crabs Carcinus maenas. In seawater (32 ppt), this decapod crustacean is osmo-conforming and therefore the majority of the observed responses can be attributed to ion fluxes based on acid-base compensatory responses alone. Similar to what is observed in brackish-water acclimated C. maenas, seawater-acclimated green crabs exposed to environmental hypercapnia rapidly accumulated HCO3- in their hemolymph to compensate for the respiratory acidosis caused by excess hemolymph pCO2 after only 24 48 hours. A full recovery of the decreased hemolymph pH was not observed in this time frame. Isolated gill perfusion experiments on anterior gill 5 applying inhibitors for potential key-transporters located in the crabs’ gill epithelium supported the involvement of all investigated genes in ammonia excretion and the excretion of acid-base equivalents. The most significant effect was observed targeting basolateral applied Na+/HCO3--cotransporter and V-ATPase. Under the influence of these two inhibitors the excretion of H+ and partly for CO2 was reversed and an enrichment of these two molecules in the hemolymph was observed. A working model for acid-base regulatory mechanisms and their link to ammonia excretion in the gill epithelium of C. maenas has been hypothesized including basolateral Na+/HCO3--cotransporter, V-ATPase, Na+/H+-exchanger, Na+/K+-ATPase, carbonic anhydrase and K+-channels. The data of the present study suggests transport of CO2 and NH4+ in acidified and non-acidified vesicles.