Rapid regulation of blood parameters under acute hypoxia in the Amazonian fish Prochilodus nigricans.
Prochilodus nigricans, locally known as curimatã, is an Amazonian commercial fish that endures adverse environmental conditions, in particular low dissolved oxygen, during its migration. Poorer environmental conditions are expected in the near future. Prochilodus nigricans overcomes current seasonal and diurnal changes in dissolved oxygen by adjusting erythrocytic levels of ATP and GTP, modulators of Hb-O2 affinity. Will this fish species be endangered under more extreme environmental conditions as hypoxia and acidification tend to occur in a shorter period of time? As P. nigricans does not exhibit any apparent morphological alterations to exploit the air-water interface, it must rely on fast adjustments of blood properties. To investigate this aspect, basic hematology indices, pHe, pHi, plasma lactate, erythrocytic levels of ATP and GTP and functional properties of the hemolysate of P. nigricans were analyzed over a period of 6h in hypoxia and subsequent recovery in normoxia. The levels of erythrocytic GTP were four times higher than ATP and were reduced to ¼ of the original level after 3h under hypoxia. Erythrocytic levels of ATP were unaffected over the experimental period. All other analyzed blood parameters exhibited a time-course change in animals under hypoxia and returned to normoxic levels. Considering the hemolysate functional properties and the ability to regulate the above mentioned blood characteristics, P. nigricans is able to endure short-term changes in dissolved oxygen.
Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Ave Andre Araujo, 2936, Manaus, AM, 69080-971, Brazil. Electronic address: dalval@inpa.gov.br.
Adalberto Luis
AL
Val
Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Ave Andre Araujo, 2936, Manaus, AM, 69080-971, Brazil. Electronic address: krmaruyama@hotmail.com.
Katia Regina Maruyama
KR
Gomes
Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon, Ave Andre Araujo, 2936, Manaus, AM, 69080-971, Brazil. Electronic address: veraval@inpa.gov.br.
Vera Maria Fonseca
VM
de Almeida-Val
D000818:Animals; D001938:Brazil; D005399:Fishes / Q000097:blood*; D000860:Hypoxia / Q000097:blood*; D010100:Oxygen / Q000097:blood
D010100:Oxygen
ATP; Blood properties; GTP; Hemoglobin modulators; Tropical fish