Regulation by the exogenous polyamine spermidine of Na,K-ATPase activity from the gills of the euryhaline swimming crab Callinectes danae (Brachyura, Portunidae)
| Autor: | Francisco de Assis Leone, Fernando Luis Medina Mantelatto, John Campbell McNamara, Rosa dos Prazeres Melo Furriel, Helena M. Scofano, Hector Barrabin, E. C. C. Silva, Carlos Frederico Leite Fontes, D. C. Masui |
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| Rok vydání: | 2008 |
| Předmět: |
Gills
Brachyura Spermidine Physiology Oceans and Seas Sodium Sodium-Potassium-Exchanging ATPase chemistry.chemical_element Spermine Fresh Water Biology Biochemistry chemistry.chemical_compound Adenosine Triphosphate Animals Na+/K+-ATPase Molecular Biology Hydrolysis Euryhaline Quaternary Ammonium Compounds Kinetics chemistry Potassium Putrescine Polyamine |
| Zdroj: | Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 149:622-629 |
| ISSN: | 1096-4959 |
| Popis: | Euryhaline crustaceans rarely hyporegulates and employ the driving force of the Na,K-ATPase, located at the basal surface of the gill epithelium, to maintain their hemolymph osmolality within a range compatible with cell function during hyper-regulation. Since polyamine levels increase during the adaptation of crustaceans to hyperosmotic media, we investigate the effect of exogenous polyamines on Na,K-ATPase activity in the posterior gills of Callinectes danae, a euryhaline swimming crab. Polyamine inhibition was dependent on cation concentration, charge and size in the following order: spermine>spermidine>putrescine. Spermidine affected K(0.5) values for Na(+) with minor alterations in K(0.5) values for K(+) and NH(4)(+), causing a decrease in maximal velocities under saturating Na(+), K(+) and NH(4)(+) concentrations. Phosphorylation measurements in the presence of 20 microM ATP revealed that the Na,K-ATPase possesses a high affinity site for this substrate. In the presence of 10 mM Na(+), both spermidine and spermine inhibited formation of the phosphoenzyme; however, in the presence of 100 mM Na(+), the addition of these polyamines allowed accumulation of the phosphoenzyme. The polyamines inhibited pumping activity, both by competing with Na(+) at the Na(+)-binding site, and by inhibiting enzyme dephosphorylation. These findings suggest that polyamine-induced inhibition of Na,K-ATPase activity may be physiologically relevant during migration to fully marine environments. |
| Databáze: | OpenAIRE |
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