Effect of cortisol on vasopressin response to hypertonic saline in fetal sheep.
To determine the effect of cortisol on vasopressin responses to hyperosmolality, we infused hypertonic saline (HS) (12 meq/kg NaCl) into nine chronically cannulated fetal sheep ranging from 110 to 132 days of gestation. The experiment was performed twice on each fetus, once during a continuous cortisol infusion and once during a vehicle infusion. Administration of HS resulted in a prompt increase in serum osmolality from 292.1 +/- 1.8 to 310.4 +/- 2.5 mosmol/kg. Decreases were seen in pH, partial pressure of O2, and hematocrit from 7.37 +/- 0.01 to 7.31 +/- 0.01, from 22.5 +/- 1.6 to 20.0 +/- 2.0 mmHg, and from 35.6 +/- 1.7 to 32.6 +/- 1.6, respectively. Mean arterial pressure increased from 41.3 +/- 1.4 to 48.9 +/- 2.0 mmHg (P less than 0.01). Arginine vasopressin (AVP) rose from base line after HS (P = 0.11 vehicle experiments, P = 0.04 cortisol experiments), and AVP responses were greater in the cortisol experiments than in the vehicle experiments (delta AVP = 21.9 +/- 10.9 vs. 3.1 +/- 0.9 pg/ml, P = 0.05). Also there was a correlation noted between differences in AVP response and cortisol levels (P less than 0.04). We conclude that cortisol exerts a positive influence on the AVP response to HS in fetal sheep.
Bennett
T L
TL
Department of Obstetrics and Gynecology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27103.
Rose
J C
JC
D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood / Q000378:metabolism*; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000032:analysis*; D005333:Fetus / Q000502:physiology; D006340:Heart Rate, Fetal / Q000187:drug effects; D006400:Hematocrit; D006854:Hydrocortisone / Q000097:blood / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D010100:Oxygen / Q000097:blood; D011247:Pregnancy; D012016:Reference Values; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D012756:Sheep; D014882:Water-Electrolyte Balance
D012462:Saline Solution, Hypertonic; D001127:Arginine Vasopressin; D002245:Carbon Dioxide; D010100:Oxygen; D006854:Hydrocortisone