Ionoregulatory changes in the gill epithelia of coho salmon during seawater acclimation.
Short-term exposure of coho salmon smolts (Oncorhynchus kisutch) to a gradual increase in salinity over 2 d (0 per thousand -32 per thousand ) resulted in a decrease in proton pump abundance, detected as changes in immunoreactivity with a polyclonal antibody against subunit A of bovine brain vacuolar H(+)-ATPase. N-ethylmaleimide (NEM)-sensitive H(+)-ATPase activities in gill homogenates remained unchanged over 8 d to coincide with a 3.5-fold increase in Na(+)/K(+)-ATPase activities. A transient increase in plasma [Na(+)] and [Cl(-)] levels over the 8-d period was preceded by a 10-fold increase in plasma cortisol levels, which peaked after 12 h. Long-term (1 mo) acclimation to seawater resulted in the loss of apical immunoreactivity for vH(+)-ATPase and band 3-like anion exchanger in the mitochondria-rich cells identified by high levels of Na(+)/K(+)-ATPase immunoreactivity. The polyclonal antibody Ab597 recognized a Na(+)/H(+) exchanger (NHE-2)-like protein in what appears to be an accessory cell (AC) type. Populations of these ACs were found associated with Na(+)/K(+)-ATPase rich chloride cells in both freshwater- and seawater-acclimated animals.
Bamfield Marine Station, Bamfield, British Columbia V0R 1B0, Canada.
J M
JM
Wilson
N M
NM
Whiteley
D J
DJ
Randall
D000222:Adaptation, Physiological; D000818:Animals; D002712:Chlorides / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism*; D005618:Fresh Water; D005880:Gills / Q000378:metabolism*; D017136:Ion Transport; D012474:Salmon / Q000378:metabolism*; D012623:Seawater / Q000737:chemistry*; D012964:Sodium / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution; D014882:Water-Electrolyte Balance
D002712:Chlorides; D017923:Sodium-Hydrogen Exchangers; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase