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Osmoregulation in water-deprived rats drinking hypertonic saline: effect of area postrema lesions
1 Department of Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260; and 2 Department of Psychology, Florida State University, Tallahassee, Florida 32306 Rats drank rapidly when 0.3 M NaCl was the only drinking fluid available after overnight water deprivation, consuming ~200 ml...
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Published in: | American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2001-03, Vol.280 (3), p.831-R842 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | 1 Department of Neuroscience, University of Pittsburgh,
Pittsburgh, Pennsylvania 15260; and 2 Department of
Psychology, Florida State University, Tallahassee, Florida 32306
Rats drank rapidly when 0.3 M
NaCl was the only drinking fluid available after overnight water
deprivation, consuming ~200 ml/24 h. Although such large intakes of
this hypertonic solution initially elevated plasma osmolality,
excretion of comparable volumes of urine more concentrated than 300 meq
Na + /l ultimately appears to restore plasma osmolality to
normal levels. Rats drank ~100 ml of 0.5 M NaCl after overnight water
deprivation, but urine Na + concentration (U Na )
did not increase sufficiently to achieve osmoregulation. When an
injected salt load exacerbated the initial dehydration caused by water
deprivation, rats increased U Na to void the injected load
and did not significantly alter 24-h intake of 0.3 or 0.5 M NaCl. Rats
with lesions of area postrema had much higher saline intakes and lower
U Na than did intact control rats; nonetheless, they
appeared to osmoregulate well while drinking 0.3 M NaCl but not while
drinking 0.5 M NaCl. Detailed analyses of drinking behavior by intact
rats suggest that individual bouts were terminated by some rapid
postabsorptive consequence of the ingested NaCl load that inhibited
further NaCl intake, not by a fixed intake volume or number of licks
that temporarily satiated thirst.
oxytocin; thirst; vasopressin |
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ISSN: | 0363-6119 1522-1490 |
DOI: | 10.1152/ajpregu.2001.280.3.r831 |