2 Electrophysiology of Ion Transport in Teleost Intestinal Cells

Digestive tract ontogeny of Dicentrarchus labrax: Implication in osmoregulation

“…From D0, fluorescence was located in the basolateral compartment of both intestinal and rectal epithelial cells, as reported in the trout (Seidelin et al 1999). Such a distribution is consistent with the models already proposed in SWadapted fish for the intestine concerning the flux of Na + from the lumen to the intercellular compartment and the serosa, creating thereby a favorable gradient for Na + influx at the apical membrane, followed by water absorption (Gibson et al 1987;Loretz 1995;Marshall & Bryson 1998;Schettino & Lionetto 2003;Trischitta et al 2004). The abundance of fluorescence along the intestinal brush border suggests a function restricted to water and nutriment absorption (Buddington & Kuz'mina 2000;Aoki et al 2003).…”

Digestive tract ontogeny of Dicentrarchus labrax: Implication in osmoregulation

“…From D0, fluorescence was located in the basolateral compartment of both intestinal and rectal epithelial cells, as reported in the trout (Seidelin et al 1999). Such a distribution is consistent with the models already proposed in SWadapted fish for the intestine concerning the flux of Na + from the lumen to the intercellular compartment and the serosa, creating thereby a favorable gradient for Na + influx at the apical membrane, followed by water absorption (Gibson et al 1987;Loretz 1995;Marshall & Bryson 1998;Schettino & Lionetto 2003;Trischitta et al 2004). The abundance of fluorescence along the intestinal brush border suggests a function restricted to water and nutriment absorption (Buddington & Kuz'mina 2000;Aoki et al 2003).…”

Plasticity of osmoregulatory function in the killifish intestine:drinking rates, salt and water transport, and gene expression after freshwater transfer

“…Our data are in accord with the general view, based mainly on similar in vitro studies with seawater fish, that an isosmotic solution is absorbed across the intestine of fish (Loretz, 1995). The slope of the relationship in Fig.·5 of this study indicates that the strong ion concentration of the absorbed fluid was about 292·mmol·l -1 (see Results), which would make it nearly isosmotic to blood plasma and to the incubation saline (note this neglects the small contribution from the unmeasured cation/anion, as discussed below).…”

Inhibition of goby posterior intestinal NaCl absorption by natriuretic peptides and by cardiac extracts

“…Another possible source of elevated GT might be the increased cellular K + conductance. Consistent with the general finding in the goby intestine of cellular hyperpotarization by agents which inhibit Na+-C1 -and Na+-K+-2C1 -cotransport (Loretz 1995b), the apical membrane potential of goby posterior intestinal cells was hyperpolarized following exposure to eANP (Loretz 1995c); this may have resulted from activation of Ca 2 +-activated K +chan-nels, known to exist in teleost enterocytes (Loretz and Fourtner 1991;O'Grady et al 1991), following NPinduced elevations of intracellular Ca 2+ activity ([ Caz + ]i; discussed below). Interestingly, the pattern of electrical response differs between the goby and the flounder intestine.…”

Digestive tract ontogeny of Dicentrarchus labrax: Implication in osmoregulation

“…From D0, fluorescence was located in the basolateral compartment of both intestinal and rectal epithelial cells, as reported in the trout (Seidelin et al 1999). Such a distribution is consistent with the models already proposed in SWadapted fish for the intestine concerning the flux of Na + from the lumen to the intercellular compartment and the serosa, creating thereby a favorable gradient for Na + influx at the apical membrane, followed by water absorption (Gibson et al 1987;Loretz 1995;Marshall & Bryson 1998;Schettino & Lionetto 2003;Trischitta et al 2004). The abundance of fluorescence along the intestinal brush border suggests a function restricted to water and nutriment absorption (Buddington & Kuz'mina 2000;Aoki et al 2003).…”

Plasticity of osmoregulatory function in the killifish intestine:drinking rates, salt and water transport, and gene expression after freshwater transfer

“…Our data are in accord with the general view, based mainly on similar in vitro studies with seawater fish, that an isosmotic solution is absorbed across the intestine of fish (Loretz, 1995). The slope of the relationship in Fig.·5 of this study indicates that the strong ion concentration of the absorbed fluid was about 292·mmol·l -1 (see Results), which would make it nearly isosmotic to blood plasma and to the incubation saline (note this neglects the small contribution from the unmeasured cation/anion, as discussed below).…”

Inhibition of goby posterior intestinal NaCl absorption by natriuretic peptides and by cardiac extracts

“…Another possible source of elevated GT might be the increased cellular K + conductance. Consistent with the general finding in the goby intestine of cellular hyperpotarization by agents which inhibit Na+-C1 -and Na+-K+-2C1 -cotransport (Loretz 1995b), the apical membrane potential of goby posterior intestinal cells was hyperpolarized following exposure to eANP (Loretz 1995c); this may have resulted from activation of Ca 2 +-activated K +chan-nels, known to exist in teleost enterocytes (Loretz and Fourtner 1991;O'Grady et al 1991), following NPinduced elevations of intracellular Ca 2+ activity ([ Caz + ]i; discussed below). Interestingly, the pattern of electrical response differs between the goby and the flounder intestine.…”

Digestive tract ontogeny of Dicentrarchus labrax: Implication in osmoregulation

“…From D0, fluorescence was located in the basolateral compartment of both intestinal and rectal epithelial cells, as reported in the trout (Seidelin et al 1999). Such a distribution is consistent with the models already proposed in SWadapted fish for the intestine concerning the flux of Na + from the lumen to the intercellular compartment and the serosa, creating thereby a favorable gradient for Na + influx at the apical membrane, followed by water absorption (Gibson et al 1987;Loretz 1995;Marshall & Bryson 1998;Schettino & Lionetto 2003;Trischitta et al 2004). The abundance of fluorescence along the intestinal brush border suggests a function restricted to water and nutriment absorption (Buddington & Kuz'mina 2000;Aoki et al 2003).…”

Plasticity of osmoregulatory function in the killifish intestine:drinking rates, salt and water transport, and gene expression after freshwater transfer

“…Our data are in accord with the general view, based mainly on similar in vitro studies with seawater fish, that an isosmotic solution is absorbed across the intestine of fish (Loretz, 1995). The slope of the relationship in Fig.·5 of this study indicates that the strong ion concentration of the absorbed fluid was about 292·mmol·l -1 (see Results), which would make it nearly isosmotic to blood plasma and to the incubation saline (note this neglects the small contribution from the unmeasured cation/anion, as discussed below).…”

Inhibition of goby posterior intestinal NaCl absorption by natriuretic peptides and by cardiac extracts

“…Another possible source of elevated GT might be the increased cellular K + conductance. Consistent with the general finding in the goby intestine of cellular hyperpotarization by agents which inhibit Na+-C1 -and Na+-K+-2C1 -cotransport (Loretz 1995b), the apical membrane potential of goby posterior intestinal cells was hyperpolarized following exposure to eANP (Loretz 1995c); this may have resulted from activation of Ca 2 +-activated K +chan-nels, known to exist in teleost enterocytes (Loretz and Fourtner 1991;O'Grady et al 1991), following NPinduced elevations of intracellular Ca 2+ activity ([ Caz + ]i; discussed below). Interestingly, the pattern of electrical response differs between the goby and the flounder intestine.…”