Abstract
The absorption of Cl - and water from ingested seawater in the marine fish intestine is accomplished partly through Cl -/HCO 3 - exchange. Recently, a H - pump (vacuolar-type H +-ATPase) was found to secrete acid into the intestinal lumen, and it may serve to titrate luminal HCO 3 - and facilitate further Cl -/HCO 3 - exchange, especially in the posterior intestine, where adverse concentration gradients could limit Cl -/HCO 3 - exchange. The H + pump is expressed in all intestinal segments and in gill tissue of gulf toadfish (Opsanus beta) maintained in natural seawater. After acute transfer of toadfish to 60 ppt salinity, H + pump expression increased 20-fold in the posterior intestine. In agreement with these observations was a fourfold-increased H +- ATPase activity in the posterior intestine of animals acclimated to 60 ppt salinity. Interestingly, Na +-K +-ATPase activity was elevated in the anterior intestine and gill, but not in the posterior intestine. Apical acid secretion by isolated intestinal tissue mounted in Ussing chambers fitted with pH-stat titration systems increased after acclimation to hypersalinity in the anterior and posterior intestine, titrating >20% of secreted bicarbonate. In addition, net base secretion increased in hypersalinity-acclimated fish and was ~70% dependent on serosal HCO 3 -. Protein localization by immunohistochemistry confirmed the presence of the vacuolar-type H +-ATPase in the apical region of intestinal enterocytes. These results show that the H + pump, especially in the posterior intestine, plays an important role in hypersaline osmoregulation and that it likely has significant effects on HCO 3 - accumulation in the intestinal lumen and, therefore, the continued absorption of Cl - and water.
| Original language | English |
|---|---|
| Pages (from-to) | 1682-1691 |
| Number of pages | 10 |
| Journal | American Journal of Physiology - Regulatory Integrative and Comparative Physiology |
| Volume | 301 |
| Issue number | 6 |
| DOIs | |
| State | Published - Dec 1 2011 |
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Keywords
- Ion transport
- Ph-stat titration
- Posterior intestine
- Salinity
- Water absorption
ASJC Scopus subject areas
- Physiology
- Physiology (medical)
Cite this
Regulation of apical h +-atpase activity and intestinal HCO 3 - secretion in marine fish osmoregulation. / Guffey, S.; Esbaugh, A.; Grosell, Martin.
In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 301, No. 6, 01.12.2011, p. 1682-1691.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Regulation of apical h +-atpase activity and intestinal HCO 3 - secretion in marine fish osmoregulation
AU - Guffey, S.
AU - Esbaugh, A.
AU - Grosell, Martin
PY - 2011/12/1
Y1 - 2011/12/1
N2 - The absorption of Cl - and water from ingested seawater in the marine fish intestine is accomplished partly through Cl -/HCO 3 - exchange. Recently, a H - pump (vacuolar-type H +-ATPase) was found to secrete acid into the intestinal lumen, and it may serve to titrate luminal HCO 3 - and facilitate further Cl -/HCO 3 - exchange, especially in the posterior intestine, where adverse concentration gradients could limit Cl -/HCO 3 - exchange. The H + pump is expressed in all intestinal segments and in gill tissue of gulf toadfish (Opsanus beta) maintained in natural seawater. After acute transfer of toadfish to 60 ppt salinity, H + pump expression increased 20-fold in the posterior intestine. In agreement with these observations was a fourfold-increased H +- ATPase activity in the posterior intestine of animals acclimated to 60 ppt salinity. Interestingly, Na +-K +-ATPase activity was elevated in the anterior intestine and gill, but not in the posterior intestine. Apical acid secretion by isolated intestinal tissue mounted in Ussing chambers fitted with pH-stat titration systems increased after acclimation to hypersalinity in the anterior and posterior intestine, titrating >20% of secreted bicarbonate. In addition, net base secretion increased in hypersalinity-acclimated fish and was ~70% dependent on serosal HCO 3 -. Protein localization by immunohistochemistry confirmed the presence of the vacuolar-type H +-ATPase in the apical region of intestinal enterocytes. These results show that the H + pump, especially in the posterior intestine, plays an important role in hypersaline osmoregulation and that it likely has significant effects on HCO 3 - accumulation in the intestinal lumen and, therefore, the continued absorption of Cl - and water.
AB - The absorption of Cl - and water from ingested seawater in the marine fish intestine is accomplished partly through Cl -/HCO 3 - exchange. Recently, a H - pump (vacuolar-type H +-ATPase) was found to secrete acid into the intestinal lumen, and it may serve to titrate luminal HCO 3 - and facilitate further Cl -/HCO 3 - exchange, especially in the posterior intestine, where adverse concentration gradients could limit Cl -/HCO 3 - exchange. The H + pump is expressed in all intestinal segments and in gill tissue of gulf toadfish (Opsanus beta) maintained in natural seawater. After acute transfer of toadfish to 60 ppt salinity, H + pump expression increased 20-fold in the posterior intestine. In agreement with these observations was a fourfold-increased H +- ATPase activity in the posterior intestine of animals acclimated to 60 ppt salinity. Interestingly, Na +-K +-ATPase activity was elevated in the anterior intestine and gill, but not in the posterior intestine. Apical acid secretion by isolated intestinal tissue mounted in Ussing chambers fitted with pH-stat titration systems increased after acclimation to hypersalinity in the anterior and posterior intestine, titrating >20% of secreted bicarbonate. In addition, net base secretion increased in hypersalinity-acclimated fish and was ~70% dependent on serosal HCO 3 -. Protein localization by immunohistochemistry confirmed the presence of the vacuolar-type H +-ATPase in the apical region of intestinal enterocytes. These results show that the H + pump, especially in the posterior intestine, plays an important role in hypersaline osmoregulation and that it likely has significant effects on HCO 3 - accumulation in the intestinal lumen and, therefore, the continued absorption of Cl - and water.
KW - Ion transport
KW - Ph-stat titration
KW - Posterior intestine
KW - Salinity
KW - Water absorption
UR - http://www.scopus.com/inward/record.url?scp=82755164897&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=82755164897&partnerID=8YFLogxK
U2 - 10.1152/ajpregu.00059.2011
DO - 10.1152/ajpregu.00059.2011
M3 - Article
C2 - 21865541
AN - SCOPUS:82755164897
VL - 301
SP - 1682
EP - 1691
JO - American Journal of Physiology - Cell Physiology
JF - American Journal of Physiology - Cell Physiology
SN - 0363-6143
IS - 6
ER -