Decrease of brain extracellular fluid [Na] and its interaction with other factors influencing sodium appetite in sheep.
It has been shown previously in sheep that physiological increase of cerebrospinal fluid (CSF) [Na] by infusion of 0.5 M NaCl artificial CSF causes a large reduction of sodium appetite of the sodium-deplete animal. Equivalent increase of CSF osmotic pressure caused by infusion 0.7 M mannitol artificial CSF which lowers CSF [Na] causes a doubling of sodium appetite. The results of the experiments here show that simple dilution of CSF [Na] with isotonic mannitol CSF, as distinct from use of hypertonic 0.7 M mannitol CSF, is an equally effective strong stimulus of sodium appetite. Lowering CSF [Na] concentration stimulates salt appetite in the severely sodium-deplete as well as in the mild to moderately sodium-deplete animal, and the effect of decrease of CSF [Na] on sodium appetite is sustained over 48 h. In addition, i.c.v. infusion of angiotensin II for the preceding 22 h at a rate which is an effective stimulus of both water and sodium solution intake in the sodium-replete animal, in fact, significantly decreased the sodium appetite stimulating effect of reduction of CSF [Na] in the Na-deplete animal.
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D002555:Cerebrospinal Fluid / Q000187:drug effects / Q000502:physiology*; D004327:Drinking Behavior / Q000187:drug effects / Q000502:physiology*; D005260:Female; D007276:Injections, Intraventricular; D008353:Mannitol / Q000494:pharmacology; D010949:Plasma / Q000187:drug effects / Q000378:metabolism; D012463:Saliva / Q000378:metabolism; D012756:Sheep / Q000502:physiology*; D012964:Sodium / Q000502:physiology* / Q000652:urine
D000804:Angiotensin II; D008353:Mannitol; D012964:Sodium