| low ph and calcium effects on net na+ and k+ fluxes in two catfish species from the amazon river (corydoras: callichthyidae). | the present study analyzes na+ and k+ disturbances caused by low ph in two catfish species from the amazon river. corydoras adolfoi inhabits ion-poor, black-stained, low ph (3.5-4.0) waters, while c. schwartzi is native to ion-rich waters at circumneutral ph. fish were exposed to ph 3.5 ca2+-free, and ca2+-enriched (approximately 500 micromol/l) water to determine the protective effects of calcium. net na+ and k+ fluxes were measured in the water collected from the fish experimental chambers. c. ... | 2002 | 11887215 |