Effects of caecal ligation and saline acclimation on plasma concentration and organ mass in male and female Pekin ducks,Anas platyrhynchos |
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Authors: | Maryanne R Hughes David Kojwang Tania Zenteno-Savin |
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Institution: | (1) Department of Zoology, University of British Columbia, 6270 University Boulevard, V6T 1Z4 Vancouver, British Columbia, Canada |
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Abstract: | Summary The intestinal caeca reabsorb urinary sodium chloride (NaCl) and water (Rice and Skadhauge 1982). Free water may be generated if the reabsorbed NaCl is secreted via salt gland secretion (Schmidt-Nielsen et al. 1958). Therefore ceacal ligation should (a) reduce hingut NaCl and water reabsorption, (b) enhance the increase in plasma osmolality during saline acclimation, and (c) affect drakes more than ducks. Twelve Pekin drakes and 13 Pekin ducks, Anas platyrhynchos, were caecally ligated or sham operated before acclimation to 450 mmol · 1 NaCl. Body mass, hematocrit, plasma osmolality, and inonic concentrations of plasma, cloacal fluid, and salt gland secretion were measured after each increase in drinking water salinity. Osmoregulatory organ masses were determined. Caecal ligation did not effect plasma osmolality or ion concentrations of plasma, cloacal fluid, or salt gland secretion, but reduced salt gland size in ducks. Drakes and ducks drinking fresh water had the same hematocrit, plasma osmolality, and plasma concentrations of Na+ and Cl–. In both sexes exposure to 75 mmol · 1-1 NaCl significantly decreased plasma Na+] and doubled cloacal fluid Na+]. Exposure to 450 mmol · 1-1 NaCl decreased body mass and increased hematocrit, plasma Na+], Cl–], and plasma osmolality (more in drakes than in ducks); cloacal fluid osmolality nearly doubled compared to freshwater-adapted ducks, due mainly to osmolytes other than Na+ and Cl–. The Cl–] in salt gland secretion only slightly exceeded drinking water Cl–].Abbreviations
AVT
antiduretic hormone
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CF
cloacal fluid
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ECFV
extraoellular fluid volume
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FW
freshwater acclimated
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Hct
hematocrit
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MDWE
mean daily water flux
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Na
+]cf
cloacal fluid sodium concentration
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Na
+]pl
plasma sodium concentration
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Osm
cf
cloacal fluid osmolality
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Osm
pl
plasma osmolality
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SGS
salt gland secretion
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TBW
total body water |
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Keywords: | Salt acclimation Salt gland secretion Cloacal excretion Osmoregulation Caecal ligation Pekin duck Anas platyrhynchos |
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