Drinking after intragastric NaCl without increase in systemic plasma osmolality in rats.
Drinking after intragastric hypertonic solutions was examined to determine whether increased plasma osmolality always accompanied initiation of drinking. A 2-ml infusion through a gastric catheter was the beginning of tests in Sprague-Dawley male rats. Latency to drink was shorter and 1-h water intake was greater for increasing concentrations of NaCl (600, 1,200, and 1,800 mosmol/kg) compared with baseline (290 mosmol/kg). Although 600, 900, or 1,200 mosmol/kg NaCl elicited drinking, such infusions failed to change systemic plasma osmolality, and 900 mosmol/kg also failed to change plasma sodium, protein, renin activity, or packed cell volume at the initiation of drinking. Intragastric 900 mosmol/kg sodium bicarbonate, sodium isethionate, potassium chloride, lithium chloride, and mannitol differentially increased water intake. Total subdiaphragmatic vagotomy abolished drinking elicited by intragastric NaCl; selective gastric or hepatic vagotomy attenuated intake under some conditions. These results support the hypothesis of a vagally mediated, gastrointestinal and/or hepatic-portal, osmosensitive mechanism for initiation of drinking in advance of postprandial increases in systemic osmolality.
Kraly
F S
FS
Department of Psychology, Colgate University, Hamilton, New York 13346, USA.
Kim
Y M
YM
Dunham
L M
LM
Tribuzio
R A
RA
D000818:Animals; D001769:Blood / Q000378:metabolism*; D001798:Blood Proteins / Q000032:analysis; D002404:Catheterization; D004326:Drinking / Q000187:drug effects*; D006400:Hematocrit; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D017207:Rats, Sprague-Dawley; D012083:Renin / Q000097:blood; D012964:Sodium / Q000097:blood; D012965:Sodium Chloride / Q000008:administration & dosage* / Q000494:pharmacology; D013270:Stomach; D014628:Vagotomy
D001798:Blood Proteins; D012965:Sodium Chloride; D012964:Sodium; D012083:Renin