Plasma concentrations of adrenocorticotropin-related peptides after corticotropin-releasing hormone and vasopressin injections in sheep.
Ovine corticotropin-releasing hormone (1 micrograms/kg body weight) and arginine vasopressin (1 micrograms/kg) were injected iv in sheep, both separately and in combination. Plasma were sampled just before and 5, 15 and 30 min after the injection. Adrenocorticotropin-related peptides were isolated by Sephadex G-50 column chromatography and measured by RIA. Cortisol and aldosterone were determined on the same plasma samples. Three molecular forms of immunoreactive ACTH (IR-ACTH) were isolated: 'big' (greater than 20,000 mol wt), 'intermediate' (= 8000 mol wt) and 'little' (= 4500 mol wt). Following CRH injections, the three molecular forms of ACTH were enhanced, particularly the 'little' form, whereas 'intermediate' IR-ACTH was highly and specifically responsive to AVP. After a simultaneous injection of CRH and AVP, additive increases occurred for 'intermediate' and 'little' IR-ACTH. The release of different molecular forms of IR-ACTH after stimulation by CRH or AVP of corticotrope cells suggests that ACTH-related peptides could be stored in different intracellular pools or secreted by different pituitary cells.
Pradier
P
P
Laboratoire de Physiologie Animale, Université Blaise Pascal/Clermont II, Aubiére, France.
Dalle
M
M
Tournaire
C
C
Delost
P
P
D000324:Adrenocorticotropic Hormone / Q000097:blood*; D000450:Aldosterone / Q000097:blood; D000818:Animals; D001127:Arginine Vasopressin / Q000008:administration & dosage*; D002850:Chromatography, Gel; D003346:Corticotropin-Releasing Hormone / Q000008:administration & dosage*; D005260:Female; D006854:Hydrocortisone / Q000097:blood; D015394:Molecular Structure; D011863:Radioimmunoassay; D012756:Sheep
D001127:Arginine Vasopressin; D000450:Aldosterone; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D006854:Hydrocortisone