Abstract
Marine teleosts constantly lose water to their surrounding environment, a problem exacerbated in fish exposed to salinity higher than normal seawater. Some fish undergo hypersaline exposures in their natural environments, such as shortand long-term increases in salinity occurring in small tidal pools and other isolated basins, lakes, or entire estuaries. Regardless of the degree of hypersalinity in the ambient water, intestinal absorption of monovalent ions drives water uptake to compensate for water loss, concentrating impermeable MgSO4 in the lumen. This study considers the potential of luminal [MgSO4] to limit intestinal water absorption, and therefore osmoregulation, in hypersalinity. The overall tolerance and physiological response of toadfish (Opsanus beta) to hypersalinity exposure were examined. In vivo, fish in hypersaline waters containing artificially low [MgSO4] displayed significantly lower osmolality in both plasma and intestinal fluids, and increased survival at 85 parts per thousand, indicating improved osmoregulatory ability than in fish exposed to hypersalinity with ionic ratios similar to naturally occurring ratios. Intestinal sac preparations revealed that in addition to the osmotic pressure difference across the epithelium, the luminal ionic composition influenced the absorption of Na+, Cl-, and water. Hypersalinity exposure increased urine flow rates in fish fitted with ureteral catheters regardless of ionic composition of the ambient seawater, but it had no effect on urine osmolality or pH. Overall, concentrated MgSO4 within the intestinal lumen, rather than renal or branchial factors, is the primary limitation for osmoregulation by toadfish in hypersaline environments.
| Original language | English |
|---|---|
| Journal | American Journal of Physiology - Regulatory Integrative and Comparative Physiology |
| Volume | 300 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 1 2011 |
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Keywords
- Gill
- Kidney
- Osmoregulation
- Toadfish
- Water absorption
ASJC Scopus subject areas
- Physiology
- Physiology (medical)
- Medicine(all)
Cite this
Concentration of MgSO4 in the intestinal lumen of Opsanus beta limits osmoregulation in response to acute hypersalinity stress. / Genz, Janet; Mcdonald, Danielle M; Grosell, Martin.
In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 300, No. 4, 01.04.2011.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Concentration of MgSO4 in the intestinal lumen of Opsanus beta limits osmoregulation in response to acute hypersalinity stress
AU - Genz, Janet
AU - Mcdonald, Danielle M
AU - Grosell, Martin
PY - 2011/4/1
Y1 - 2011/4/1
N2 - Marine teleosts constantly lose water to their surrounding environment, a problem exacerbated in fish exposed to salinity higher than normal seawater. Some fish undergo hypersaline exposures in their natural environments, such as shortand long-term increases in salinity occurring in small tidal pools and other isolated basins, lakes, or entire estuaries. Regardless of the degree of hypersalinity in the ambient water, intestinal absorption of monovalent ions drives water uptake to compensate for water loss, concentrating impermeable MgSO4 in the lumen. This study considers the potential of luminal [MgSO4] to limit intestinal water absorption, and therefore osmoregulation, in hypersalinity. The overall tolerance and physiological response of toadfish (Opsanus beta) to hypersalinity exposure were examined. In vivo, fish in hypersaline waters containing artificially low [MgSO4] displayed significantly lower osmolality in both plasma and intestinal fluids, and increased survival at 85 parts per thousand, indicating improved osmoregulatory ability than in fish exposed to hypersalinity with ionic ratios similar to naturally occurring ratios. Intestinal sac preparations revealed that in addition to the osmotic pressure difference across the epithelium, the luminal ionic composition influenced the absorption of Na+, Cl-, and water. Hypersalinity exposure increased urine flow rates in fish fitted with ureteral catheters regardless of ionic composition of the ambient seawater, but it had no effect on urine osmolality or pH. Overall, concentrated MgSO4 within the intestinal lumen, rather than renal or branchial factors, is the primary limitation for osmoregulation by toadfish in hypersaline environments.
AB - Marine teleosts constantly lose water to their surrounding environment, a problem exacerbated in fish exposed to salinity higher than normal seawater. Some fish undergo hypersaline exposures in their natural environments, such as shortand long-term increases in salinity occurring in small tidal pools and other isolated basins, lakes, or entire estuaries. Regardless of the degree of hypersalinity in the ambient water, intestinal absorption of monovalent ions drives water uptake to compensate for water loss, concentrating impermeable MgSO4 in the lumen. This study considers the potential of luminal [MgSO4] to limit intestinal water absorption, and therefore osmoregulation, in hypersalinity. The overall tolerance and physiological response of toadfish (Opsanus beta) to hypersalinity exposure were examined. In vivo, fish in hypersaline waters containing artificially low [MgSO4] displayed significantly lower osmolality in both plasma and intestinal fluids, and increased survival at 85 parts per thousand, indicating improved osmoregulatory ability than in fish exposed to hypersalinity with ionic ratios similar to naturally occurring ratios. Intestinal sac preparations revealed that in addition to the osmotic pressure difference across the epithelium, the luminal ionic composition influenced the absorption of Na+, Cl-, and water. Hypersalinity exposure increased urine flow rates in fish fitted with ureteral catheters regardless of ionic composition of the ambient seawater, but it had no effect on urine osmolality or pH. Overall, concentrated MgSO4 within the intestinal lumen, rather than renal or branchial factors, is the primary limitation for osmoregulation by toadfish in hypersaline environments.
KW - Gill
KW - Kidney
KW - Osmoregulation
KW - Toadfish
KW - Water absorption
UR - http://www.scopus.com/inward/record.url?scp=79954511153&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=79954511153&partnerID=8YFLogxK
U2 - 10.1152/ajpregu.00299.2010
DO - 10.1152/ajpregu.00299.2010
M3 - Article
VL - 300
JO - American Journal of Physiology - Cell Physiology
JF - American Journal of Physiology - Cell Physiology
SN - 0363-6143
IS - 4
ER -