Mitochondrion-rich cells distribution, Na+/K+-ATPase activity and gill morphometry of the Amazonian freshwater stingrays (Chondrichthyes: Potamotrygonidae).
Detailed measurements of gill area and constituent variables (total filament number, total filament length and mean filament length), and immunolocalization of the α-subunit of Na⁺/K⁺-ATPase and Na⁺/K⁺-ATPase activity were performed on both hemibranchs of all five arches of freshwater potamotrygonid stingrays (Paratrygon aiereba and Potamotrygon sp.). Both species exhibit similar mass-specific gill area, 89.8 ± 6.6 and 91.5 ± 4.3 mm² g⁻¹ for P. aiereba and Potamotrygon sp., respectively. The density of Na⁺/K⁺-ATPase-rich MRCs and Na⁺/K⁺-ATPase activity was higher in the 4th gill arch in both species. The Na⁺/K⁺-ATPase activity was positively correlated to the Na⁺/K⁺-ATPase-rich Na⁺/K⁺-ATPase rich) mitochondrion-rich cell (MRC) distribution among the gill arches of P. aiereba but not in Potamotrygon sp. The levels Na⁺/K⁺-ATPase activity were not correlated to the gill surface area among the arches for both rays' species. Considering that the Na⁺/K⁺-ATPase-rich MRC is the main site for active ion transport in the gill epithelia and Na⁺/K⁺-ATPase activity plays a crucial role in osmoionoregulatory function, we suggesting that 4th gill arch is more relevant for osmoregulation and ion balance in these potamotrygonids.
Departamento de Morfologia, Universidade Federal do Amazonas, Avenida General Rodrigo Octávio Jordão Ramos, 3000. Coroado I, Manaus, Amazonas 69.077-000, Brazil. wduncan@ufam.edu.br
Wallice P
WP
Duncan
Naara F
NF
Silva
Marisa N
MN
Fernandes
D000818:Animals; D017753:Ecosystem; D005618:Fresh Water; D005880:Gills / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism*; D012860:Skates, Fish / Q000033:anatomy & histology* / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013045:Species Specificity
D000254:Sodium-Potassium-Exchanging ATPase