TY - JOUR
T1 - Sodium deprivation blunts hypovolemia-induced pituitary secretion of vasopressin and oxytocin in rats
AU - Stricker, E. M.
AU - Schreihofer, A. M.
AU - Verbalis, J. G.
PY - 1994
Y1 - 1994
N2 - The present investigations determined the effects of dietary sodium deprivation on the neurohypophysial secretion of arginine vasopressin (AVP) and oxytocin (OT) by rats in response to nonhypotensive hypovolemia induced by subcutaneous injection of 30% polyethylene glycol solution. In rats fed either standard sodium-rich laboratory chow or sodium-deficient diet for 8 days, AVP secretion increased gradually in proportion to plasma volume deficits up to 22-28% while pituitary secretion of OT was not stimulated. However, when hypovolemia was more pronounced, secretion of both hormones was marked in rats fed standard chow, whereas rats fed sodium-deficient diet were significantly less responsive. These effects did not reflect a general insensitivity of the neurohypophysial system because sodium-deprived and chow-fed rats secreted AVP and OT equivalently in response to intravenous infusion of 1.5 M NaCl solution. Nor did they reflect a general insensitivity to hypovolemia because sodium-deprived rats drank substantial, above-normal volumes of water after colloid treatment. Instead, the results appear to reflect a specific inhibition of stimulatory baroreceptor inputs to AVP and OT neurons during dietary sodium deprivation in rats.
AB - The present investigations determined the effects of dietary sodium deprivation on the neurohypophysial secretion of arginine vasopressin (AVP) and oxytocin (OT) by rats in response to nonhypotensive hypovolemia induced by subcutaneous injection of 30% polyethylene glycol solution. In rats fed either standard sodium-rich laboratory chow or sodium-deficient diet for 8 days, AVP secretion increased gradually in proportion to plasma volume deficits up to 22-28% while pituitary secretion of OT was not stimulated. However, when hypovolemia was more pronounced, secretion of both hormones was marked in rats fed standard chow, whereas rats fed sodium-deficient diet were significantly less responsive. These effects did not reflect a general insensitivity of the neurohypophysial system because sodium-deprived and chow-fed rats secreted AVP and OT equivalently in response to intravenous infusion of 1.5 M NaCl solution. Nor did they reflect a general insensitivity to hypovolemia because sodium-deprived rats drank substantial, above-normal volumes of water after colloid treatment. Instead, the results appear to reflect a specific inhibition of stimulatory baroreceptor inputs to AVP and OT neurons during dietary sodium deprivation in rats.
UR - http://www.scopus.com/inward/record.url?scp=0028137539&partnerID=8YFLogxK
U2 - 10.1152/ajpregu.1994.267.5.r1336
DO - 10.1152/ajpregu.1994.267.5.r1336
M3 - Article
C2 - 7977862
AN - SCOPUS:0028137539
SN - 0363-6119
VL - 267
SP - R1336-R1341
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 5 36-5
ER -