We identified five Na+/K+-ATPase alpha-isoforms in rainbow trout and characterized their expression pattern in gills following seawater transfer. Three of these isoforms were closely related to other vertebrate alpha1 isoforms (designated alpha1a, alpha1b and alpha1c), one isoform was closely related to alpha2 isoforms (designated alpha2) and the fifth was closely related to alpha3 isoforms (de...

objective: the urinary system of euryhaline fish, as well as the gills, is involved in ion regulation through the production of dilute urine in freshwater and isotonic urine in seawater. the low osmolality of the urine originates from an active reabsorption of ions by ionocytes or mitochondria rich-cells (mrcs) present in certain parts of the urinary system. mitochondria rich-cells possess a hi...

Cardiac remodeling occurs after cardiac pressure/volume overload or myocardial injury during the development of heart failure and is a determinant of heart failure. Preventing or reversing remodeling is a goal of heart failure therapy. Human cardiomyocyte Na(+)/K(+)-ATPase has multiple α isoforms (1-3). The expression of the α subunit of the Na(+)/K(+)-ATPase is often altered in hypertrophic an...

Because in outer medullary collecting ducts (OMCD) of K(+)-depleted rats, K+ secretion is abolished, whereas Na+, K(+)-ATPase, which energizes this secretion, is markedly stimulated, it has been proposed that Na+, K(+)-ATPase was mislocated to the apical cell membrane and energized K+ reabsorption. This hypothesis has been supported by paradoxical effects of ouabain in K(+)-depleted compared wi...

BACKGROUND The P-type ATPase family constitutes a collection of ion pumps that form phosphorylated intermediates during ion transport. One of the best known members of this family is the Na⁺,K⁺-ATPase. The catalytic subunit of the Na⁺,K⁺-ATPase includes several functional domains that determine its enzymatic and trafficking properties. METHODOLOGY/PRINCIPAL FINDINGS Using the yeast two-hybrid...

Recent investigations demonstrate increased Na/H exchanger-1 (NHE-1) activity and plasma levels of ouabain-like factor in spontaneously hypertensive rats. At nanomolar concentrations, ouabain increases Na-K-ATPase activity, induces cell proliferation, and activates complex signaling cascades. We hypothesize that the activity of NHE-1 and Na-K-ATPase are interdependent. To test whether treatment...

Marinobufagenin (MBG), an endogenous ligand of alpha-1 Na/K-ATPase, becomes elevated and contributes to hypertension in NaCl-loaded Dahl-S rats (DS). Protein kinase C (PKC) phosphorylates alpha-1 Na/K-ATPase and increases its MBG sensitivity. Cicletanine, an antihypertensive compound with PKC-inhibitory activity, reverses MBG-induced Na/K-ATPase inhibition and vasoconstriction. We hypothesized ...

The effect of thyroxine on membrane bound (Na+, K+)-ATPase isolated as a microsomal fraction from rabbit heart and kidney was investigated. In the heart, thyroxine administration produced an increased Ki value (a concentration of ouabain required for half maximal inhibition of (Na+, K+)-ATPase activity) without alteration of the specific activity of cardiac (Na+, K+)-ATPase, indicating that the...

Multiple signaling pathways are known to induce apoptosis in thymocytes through mechanisms that include the loss of mitochondrial membrane potential, cell shrinkage, caspase activation, and DNA degradation but little is known about the consequences of apoptosis on the properties of the plasma membrane. We have previously shown that apoptotic signals, including survival factor withdrawal and glu...

The structure, ultrastructure and osmoregulatory function of the branchial chamber were investigated in Palaemon elegans (Rathke, 1837) by light microscope, electron microscope and immunohistochemistry methods, respectively. Each chamber possesses a branchiostegite, 3 epipodites and 8 phyllobranchiate gills. The lamellae are attached along the two outer surfaces of the triangular gill axis. Ult...