Glucocorticoid modulation of calcium currents in growth hormone 3 cells.
Clonal malignant pituitary growth hormone 3 cells were used for the analysis of the influence of hydrocortisone and dexamethasone on voltage-gated calcium currents and hormone secretion. The whole-cell patch-clamp technique was used. The presence of low-threshold inactivating and high-threshold persisting components in the total calcium current was shown; they could be separated at less negative holding potential level. Some increase in current densities of both components was observed as early as 30 min after treatment with 10(-6) mol/l glucocorticoids. The increase was maximal for both types of currents after 2 h of incubation; however, the high-threshold component was affected much more strongly (current density increased by more than four-fold) than the low-threshold one (current density increased by about a three-fold). Potentiation of currents was blocked by actinomycine D (10(-4) M), suggesting that protein synthesis was required. A substantial increase in growth hormone secretion (measured by radioimmunoassay method) was observed in the same cells after 2 h of incubation with hydrocortisone, while the secretion of prolactin remained even slightly depressed.
Fomina
A F
AF
Bogomoletz Institute of Physiology, Ukrainian Academy of Sciences.
Kostyuk
P G
PG
Sedova
M B
MB
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects*; D003609:Dactinomycin / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D005938:Glucocorticoids / Q000494:pharmacology*; D013006:Growth Hormone / Q000378:metabolism; D006854:Hydrocortisone / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects*; D010903:Pituitary Gland, Anterior / Q000187:drug effects* / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D051381:Rats; D014407:Tumor Cells, Cultured / Q000187:drug effects
D015220:Calcium Channels; D005938:Glucocorticoids; D003609:Dactinomycin; D003907:Dexamethasone; D011388:Prolactin; D013006:Growth Hormone; D002118:Calcium; D006854:Hydrocortisone