Hypothalamic thermal stimulation modulates vasopressin release in hyperosmotically stimulated rabbits.
Under thermoneutral conditions conscious rabbits received systemic infusions of NaCl as hypertonic solution (90 mueq.min-1.kg body wt-1), which raised their plasma osmolality from 283 to 312 mosmol/kgH2O. Rabbits receiving isotonic saline served as controls. Hypertonic stimulation induced a 60% reduction of both respiratory frequency and evaporative water loss. Rectal temperature rose by 0.4 degrees C despite enhanced peripheral vasodilation as indicated by increased ear skin temperature. Plasma vasopressin (AVP), aldosterone (ALDO), and corticosterone (COR) were significantly elevated from 6 to 16 pg/ml, 90 to 180 pg/ml, and 17 to 40 ng/ml, respectively. To elucidate the importance of central temperature for AVP and adrenal corticosteroid release, hypothalamic thermal stimulations (20 min) were superimposed during established iso- and hyperosmotic steady-state conditions. Different from isosmotic controls, hyperosmotic animals responded to hypothalamic cooling (37 degrees C) with a significant decrease in plasma AVP from 16 to 13 pg/ml and to hypothalamic warming (41 degrees C) with a significant rise from 16 to 19 pg/ml. A weak temperature effect on COR release was also disclosed, especially of hypothalamic cooling, which significantly lowered plasma COR from 42 to 34 ng/ml. These results provide evidence for positive local temperature coefficients of hypothalamic control of AVP release and suggest a similar property also for the control of COR release by the hypothalamo-adenohypophysial axis.
Keil
R
R
Max-Planck-Institut für Physiologische und Klinische Forschung, WG Kerckhoff-Institut, Bad Nauheim, Germany.
Gerstberger
R
R
Simon
E
E
D000450:Aldosterone / Q000097:blood / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation; D003080:Cold Temperature; D003345:Corticosterone / Q000097:blood / Q000378:metabolism; D005260:Female; D006400:Hematocrit; D006358:Hot Temperature; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000097:blood; D011817:Rabbits; D012119:Respiration; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D012964:Sodium / Q000097:blood; D012965:Sodium Chloride / Q000494:pharmacology; D013997:Time Factors
D012462:Saline Solution, Hypertonic; D001127:Arginine Vasopressin; D012965:Sodium Chloride; D000450:Aldosterone; D012964:Sodium; D011188:Potassium; D003345:Corticosterone