Does intracarotid PGE2 increase plasma ACTH concentration in conscious adult ewes?
The hypothesis that prostaglandin E2 (PGE2) is a circulating mediator of adrenocorticotropic hormone (ACTH) secretion in sheep was tested in conscious adult ewes using 30-min carotid artery infusions of 0, 5, 10, 100, and 500 ng.kg-1. min-1 PGE2 in saline. ACTH, cortisol, and aldosterone were significantly increased during the 500 ng.kg-1.min-1 infusion (166 +/- 61 to 233 +/- 38 pg/ml, 27 +/- 5 to 45 +/- 2 ng/ml, and 52 +/- 11 to 85 +/- 25 pg/ml, respectively). PGE2 infusions of 100 ng.kg-1.min-1 increased ACTH from 104 +/- 31 to 168 +/- 31 pg/ml and cortisol from 18 +/- 5 to 42 +/- 2 ng/ml. PGE2 infusions did not increase arginine vasopressin, plasma renin activity, or hematocrit. Heart rate and mean arterial pressure were minimally but significantly increased during the 500 ng.kg-1.min-1 infusion, from 84.9 +/- 2.8 to 99.3 +/- 5.4 beats/min and 95.5 +/- 1.8 to 101.0 +/- 3.4 mmHg, respectively. In a second study to test whether lower infusion rates of PGE2 increase plasma ACTH in sheep with lower resting hormone concentrations, sheep were infused and sampled through a tether system, preventing any disturbances due to human contact the day of an experiment. For all infusion rates ACTH baselines were less than or equal to 55 +/- 17 pg/ml, and cortisol baselines were less than or equal to 6 +/- 3 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)
Cudd
T A
TA
Department of Physiology, University of Florida, Gainesville 32610.
Wood
C E
CE
D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000450:Aldosterone / Q000097:blood; D000818:Animals; D001127:Arginine Vasopressin / Q000097:blood; D001794:Blood Pressure / Q000187:drug effects; D002339:Carotid Arteries; D015232:Dinoprostone / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006400:Hematocrit; D006854:Hydrocortisone / Q000097:blood; D007261:Infusions, Intra-Arterial; D007700:Kinetics; D012016:Reference Values; D012083:Renin / Q000097:blood; D012756:Sheep; D013997:Time Factors
D001127:Arginine Vasopressin; D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D012083:Renin; D015232:Dinoprostone; D006854:Hydrocortisone