Departamento de Morfologia, Universidade Federal do Amazonas, Avenida General Rodrigo Octávio Jordão Ramos, 3000. Coroado I, Manaus, Amazonas 69.077-000, Brazil.
Fish Physiol Biochem. 2011 Sep;37(3):523-31. doi: 10.1007/s10695-010-9454-z. Epub 2010 Dec 5.
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.
对来自五个淡水河魟鱼属（Paratrygon aiereba 和 Potamotrygon sp.）物种的每一半鳃弓的鳃面积和组成变量（总丝数量、总丝长度和平均丝长度）进行了详细测量，并对 Na⁺/K⁺-ATPase 的 α-亚基和 Na⁺/K⁺-ATPase 活性进行了免疫定位。这两个物种的单位质量特定鳃面积相似，分别为 91.5 ± 4.3 和 89.8 ± 6.6mm² g⁻¹。在这两个物种中，第四鳃弓的 Na⁺/K⁺-ATPase 丰富的线粒体丰富细胞（MRC）和 Na⁺/K⁺-ATPase 活性密度较高。Na⁺/K⁺-ATPase 活性与 P. aiereba 中鳃弓之间的 Na⁺/K⁺-ATPase 丰富的 MRC 分布呈正相关，但在 Potamotrygon sp. 中则没有相关性。在这两个射线物种的鳃弓之间，Na⁺/K⁺-ATPase 活性与鳃表面积没有相关性。考虑到 Na⁺/K⁺-ATPase 丰富的 MRC 是鳃上皮中主动离子转运的主要部位，并且 Na⁺/K⁺-ATPase 活性在渗透离子调节功能中起着至关重要的作用，我们认为第四鳃弓在这些河魟鱼属的渗透压调节和离子平衡中更为重要。
