Chloroquine Decreases Adrenocorticotrophin-Secretory Response to Corticotrophin-Releasing Factor but not to Vasopressin in Rat Pituitary Cells: Further Evidence for Differentially Responsive Subpopulations.
Abstract The relationships between adrenocorticotrophin (ACTH) content, basal ACTH secretion and the ACTH-secretory response to corticotrophin-releasing factor (CRF) or vasopressin in cultured rat anterior pituitary cells were examined in studies using chloroquine, an agent that diverts nascent ACTH from a storage pathway to direct release from cells. Chloroquine (200 mUM from t=minus 2 h) significantly elevated the basal ACTH secretory rate (by 0.7 +/- 0.2 ng over 30 min incubation, 1.1 +/- 0.3 ng over 60 min and 2.3 +/- 0.6 ng over 120 min). It also decreased the ACTH-secretory response to CRF (2.9+/-0.5 vs 4.6 +/- 0.5 ng/well over 30 min; 4.3 +/- 0.7 vs 8.0 +/- 1.4 ng/well over 60 min; 12.4+/-1.7 vs 20.2 +/- 3.6 ng/well over 120 min). In marked contrast, the net responses to vasopressin were unaltered (0.9 +/- 0.3 vs 0.9+/-0.2 ng/well over 30 min; 2.2 +/- 0.9 vs 2.1 +/-0.3 ng/well over 60 min; 3.8+/-0.9 vs 3.3 +/- 1.0 ng/well over 120 min). These data further support the association of the ACTH-secretory response to CRF with stored cellular ACTH, and the minimal dependence of the response to vasopressin on stored ACTH.
Schwartz
J
J
Medical Research Centre, Prince Henry's Hospital, St. Kilda Road, Melbourne, Australia 3004.
Pham
T
T
Funder
J W
JW