Effect of dopamine on ouabain-insensitive Na+-ATPase activity in muscle of Neohelice granulata

PINONI,S.A.; MENDEZ, E.; CARUSO-NEVES, C; LÓPEZ MAÑANES, A,A.

Encuentro; XVI Annual Meeting Argentine Biology Society; 2014

We have shown the occurrence and salinity sensibility of K+-independent, ouabain-insensitive, furosemide-sensitive Na+-ATPase activity (NA) in muscle of the euryhaline crab N. granulata. The possible regulation of this enzyme by biogenic amines (i.e. dopamine, DA) is unknown. Aim: to study the in vitro effect of DA on NA in muscle. Adult male crabs were maintained for 30d at 35? salinity. Muscle slices were incubated in the absence and in the presence of DA (10-5-10-3M) or DA10-3M+SCH23390 (D1 antagonist) 10-4M (100mg/2ml medium mM: 400 NaCl, 13 KCl, 10 MgCl2 8.8 H3BO3, pH 7.6, 30ºC). NA was determined, after 0-90min of incubation, in homogenates of tissue slices (0.25M sucrose/0.5mM EGTA-Tris, pH 7.4 8ml/g). NA was measured by ATP hydrolysis (3mM, A700nm) in a reaction medium (mM: 130 NaCl, 10 MgCl2, 0.5 EGTA, 1 ouabain, 1Na3N, in 20 imidazole buffer, pH 7.4), without or with of 2mM furosemide. NA was estimated as the difference between the two assays. NA was lower after 45min with DA10-3M (Control:119±17, DA:54±19nmolPi/min/mg prot) (n=10, paired t-test, p