The role of the transbranchial potential difference in hyperosmotic regulation of the shore crabCarcinus maenas

Abstract

When isolated gills of the shore crab Carcinus maenas were bathed and perfused with identical solutions on both sides (50 % sea water), a spontaneous transepithelial potential difference (PD) of some millivolts (hemolymph side negative) was established. This PD is of active nature and requires the metabolism of the living cell, since it uses its own sources of energy in addition to organic nutrients offered in the flow of artificial hemolymph. Addition of sodium cyanide and dinitrophenole to bathing and perfusion medium resulted in reversible breakdown of PDs in a concentration-dependent mode. In posterior gills of C. maenas, the potential differences were more negative compared to data measured in anterior gills of the same individuals. These results are correlated with higher specific activities of Na-K-ATPase in posterior gills. Experiments with triamterene indicate that sodium uptake in C. maenas is sensitive to this diuretic drug, when applied on the apical side of the epithelial cell. The results obtained show that active uptake of sodium from medium to blood across the g~s is performed by a complex mechanism including participation of several basal and apical transport steps.

Emersion and recovery alter oxygen consumption, ammonia and urea excretion, and oxidative stress parameters, but not diffusive water exchange or transepithelial potential in the green crab (Carcinus maenas)

“…In the present work, the TEP for C. maenas submerged in 100% seawater was −1.5±0.3 mV. This value is in accordance with several previous measurements on intact green crabs in 100% seawater (Greenaway, 1976;Zanders, 1980;Winkler, 1986;Dal Pont et al, 2022). The lack of significant change at the end of emersion and throughout subsequent recovery suggests that disturbances in gill permeability and transport functions during air exposure were minimal.…”

Goniopsis cruentata: caracterização cinética e bioquímica da (Na+, K+)-ATPase do tecido branquial e análise da sequência de RNAm

“…Por ser parte da família das P-ATPases, uma característica importante a ser ressaltada é que, pode ser encontrada em duas conformações principais, E1 e/ou E2. (HORISBERGER et al, 2004 Nesta conformação, os dois K + estão ocluídos no interior da enzima (JORGENSEN et al, 1998(JORGENSEN et al, , 2003KAPLAN, 2002;HORISBERGER, 2004 , 1986;ALMANSA et al, 2003;TOWLE & COPENHAVER, 1970;HARRIS, 1985;ELSE & WU, 1999). Uma alteração neste microambiente que favoreça a fluidez da membrana, irá consequentemente aumentar a atividade enzimática (BYSTRIANSKY & BALLANTYNE, 2006).…”

“…Entretanto, ainda permanece indefinido se o aumento na atividade (Na + ,K + )-ATPase é resultado da síntese de RNAm, ou se está relacionado com processos pós-traducionais ). Zanders & Martelo (1984, 1986, o animal além de hiperregular em baixas salinidades também hiporegula em salinidades mais elevadas, como já reportado para o caranguejo estuarino semi-terrestre Chasmagnathus granulatus (LUQUET et al, 2002;CHARMANTIER et al, 2002;LUQUET et al, 2005). (LUQUET et al, 2005).…”