Calcium-sensitive cells of the pars intermedia and osmotic balance in the eel. II. Response to calcium-free sea water.
Freshwater eels were adapted to calcium-free sea water (SW) or 1/3 Ca-free SW. Survival was generally poor in Ca-free SW, although three eels were still in good condition after 19-30 days; survival in 1/3 Ca-free SW was excellent. Osmotic disturbances (increase of plasma osmolarity and sodium levels), which initially occur in Ca-free SW, were no longer detectable after 19-30 days, or in eels in 1/3 Ca-free SW after one month. Plasma calcium sharply decreases initially; it is less depressed after 19-30 days and in 1/3 Ca-free SW. Alterations in the mucus production may be involved in the osmotic changes. Under these conditions no clear stimulation of the calcium-sensitive (Ca-s) cells of the pars intermedia was registered, but in Ca-free SW (1/3 or full strength) the inhibitory effect normally observed in SW does not occur. In a hyperosmotic environment, other ion(s), possibly magnesium, may reduce the response of the Ca-s cells to a lack of environmental calcium.
D000811:Anguilla / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000097:blood / Q000494:pharmacology*; D008297:Male; D010902:Pituitary Gland / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000097:blood; D012623:Seawater; D012964:Sodium / Q000097:blood; D014882:Water-Electrolyte Balance / Q000187:drug effects*
D012964:Sodium; D011188:Potassium; D002118:Calcium