Modulation of ion uptake across posterior gills of the crab Chasmagnathus granulatus by dopamine and cAMP.

HALPERIN, J.; GRISELDA GENOVESE; TRESGUERRES, M.; LUQUET, C. M.

Comparative Biochemistry and Physiology. A: Comparative Physiology

Elsevier

Lugar: Victoria; Año: 2004 vol. 139 p. 103 - 109

0300-9629

Cyclic AMP (cAMP) and dopamine modulate ion uptake across isolated and perfused posterior gills of Chasmagnathus granulatusacclimated to 10x salinity. Addition of cAMP agonists, such as cp-cAMP, forskolin, and IBMX, produced a significant increase in thetransepithelial potential difference (Vte), which reflects ion transport activity. Dopamine (DA) also had a stimulatory effect on ion uptake,increasing Vte and Na+ influx, although this effect was transient, since both variables remained elevated for less than 30 min. In addition, thedose–response curve for DA concentration-Vte was biphasic, and the maximum stimulation was obtained with 10 Amol l
1. When the effectsof forskolin and DA on the Na+/K+-ATPase activity were tested, they correlated well with the Vte and Na+ influx experiments; the enzymeactivity increased significantly after preincubation of gill fragments for 10 min with forskolin or DA (51 and 64%, respectively), but therewas no effect after pre-incubation with DA for 20 min. Finally, KT5720, a specific inhibitor of cAMP-dependent protein kinase (PKA),completely abolished the stimulatory effect of DA on Vte, suggesting the involvement of PKA in this mechanism.