Ma. Masini et al., Ion transport systems in the kidney and urinary bladder of two Antarctic teleosts, Chionodraco hamatus and Trematomus bernacchii, POLAR BIOL, 24(6), 2001, pp. 440-446
Na+-K+-Cl- cotransport and Na+/K(+)AT-Pase were studied by immunohistochemi
stry in the kidney and urinary bladder of Trematomus bernacchii and Chionod
raco hamatus. The activity was correlated to the density of mitochondria. T
he first segment of the renal proximal tubule was more active than the seco
nd one. In T. bernacchii and the temperate marine teleost Pagellus bogarave
o, the immunoreactivity for the antibody to cotransporters and to the a-sub
unit of the sodium pump was stronger than in the icefish. This difference i
ndicates in the kidney of the icefish, a weaker secretory activity, a conse
quent lower osmolarity in the lumen and lower water loss, which correlates
well with the need for a greater blood volume in the icefish. The epitheliu
m of the urinary bladder in T. bernacchii, when intense immunostaining was
observed, was composed of columnar cells. In C. hamatus the columnar cells.
where the immunostaining was weaker, lined only a portion of the urinary b
ladder, the other region being composed of cuboidal cells.