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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Dopamine binding directly up-regulates (Na+, K+)-ATPase activity in the gills of the freshwater shrimp Macrobrachium amazonicum

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Lucena, Malson N. [1, 2] ; Garcon, Daniela P. [3] ; Fontes, Carlos F. L. [4] ; Fabri, Leonardo M. [2] ; Moraes, Cintya M. [2] ; McNamara, John C. [5, 6] ; Leone, Francisco A. [2]
Total Authors: 7
[1] Univ Fed Mato Grosso do Sul, Inst Biociencias, BR-79070900 Campo Grande, MS - Brazil
[2] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, Ave Bandeirantes 3900, BR-14040901 Sao Paulo, SP - Brazil
[3] Univ Fed Triangulo Mineiro, Campus Univ Iturama, BR-38280000 Uberaba, MG - Brazil
[4] Univ Fed Rio de Janeiro, Inst Bioquim Med, BR-21941590 Rio De Janeiro, RJ - Brazil
[5] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Biol, BR-14040901 Sao Paulo, SP - Brazil
[6] Univ Sao Paulo, Ctr Biol Marinha, Sao Sebastido, SP - Brazil
Total Affiliations: 6
Document type: Journal article
Web of Science Citations: 0

We examined the effects of exogenous dopamine on gill (Na+, K+)-ATPase activity in vitro in microsomal preparations from juvenile or adult freshwater shrimp, Macrobrachium amazonicum. Dopamine had no effect on enzyme activity in juveniles but stimulated activity in adult shrimp gills by approximate to 35%. Stimulation of the gill (Na+, K+)-ATPase in adult shrimps by 100 mmol L-1 dopamine was characterized kinetically by varying ATP, MgATP, and Na+ and K+ concentrations, together with inhibition by ouabain. Dopamine stimulated ATP hydrolysis by approximate to 40% obeying Michaelis-Menten kinetics, reaching V-M = 190.5 +/- 15.7 nmol Pi min(-1) mg(-1) protein, K-M remaining unaltered. Stimulation by Na+ (approximate to 50%) and K+ (approximate to 25%) revealed distinct kinetic profiles: although K-M values were similar, Na(+)stimulation followed cooperative kinetics, contrasting with the Michaelian kinetics seen for K+. Stimulation by MgATP increased activity by approximate to 30% with little change in K-M. Similar saturation profiles were seen for ouabain inhibition with very similar calculated K-I values. Our findings suggest that dopamine may be involved in hemolymph sodium homeostasis by directly binding to the gill (Na+, K+)-ATPase at a site different from ouabain, thus stimulating enzyme activity in an ontogenetic stage-specific manner. However, dopamine binding does not affect enzyme affinity for cations and ouabain. This is the first report of the direct action of dopamine in stimulating the crustacean gill (Na+, K+)-ATPase. (AU)

FAPESP's process: 16/25336-0 - Comparative biochemical study of gill (Na+, K +)- ATPase of Macrobrachium amazonicum (Heller, 1862) inhabitant of coastal and continental regions
Grantee:Francisco de Assis Leone
Support type: Regular Research Grants
FAPESP's process: 13/24252-9 - The (Na+,K+)-ATPase in osmoregulatory capacity in crab Ucides cordatus: biochemical and molecular view
Grantee:Malson Neilson de Lucena
Support type: Scholarships in Brazil - Post-Doctorate