title: Reserpine is a calcium channel antagonist in normal and GH3 rat pituitary cells.
abstract: Reserpine exerts direct effects on several tissues, including inhibition of hormone release from rat anterior pituitary cells. To test the hypothesis that reserpine may be acting as a calcium channel antagonist, normal or GH3 rat anterior pituitary cells were preincubated in reserpine or the conventional calcium channel blocker, D-600, followed by exposure to 45Ca2+ together with stimulants of calcium uptake: maitotoxin, a potent calcium channel activator; A23187, a calcium ionophore; or 50 mMK+. After incubation, the cells were harvested by vacuum filtration and cell-associated radioactivity determined. In normal cells, reserpine blocked both basal and K+-stimulated calcium uptake. Reserpine selectively blocked maitotoxin but not A23187-induced calcium uptake. In GH3 cells 9 microM reserpine and 30 microM D-600 were equally effective in blocking maitotoxin-stimulated calcium uptake. Reserpine appears to block voltage-dependent calcium channels in pituitary cells in a concentration-dependent manner but not calcium uptake caused nonspecifically by A23187.
authors.forename: I S
authors.initials: IS
authors.lastname: Login
authors.forename: A M
authors.initials: AM
authors.lastname: Judd
authors.forename: M J
authors.initials: MJ
authors.lastname: Cronin
authors.forename: T
authors.initials: T
authors.lastname: Yasumoto
authors.forename: R M
authors.initials: RM
authors.lastname: MacLeod
mesh_terms: D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers; D002460:Cell Line; D005260:Female; D005711:Gallopamil / Q000494:pharmacology; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D008387:Marine Toxins / Q000494:pharmacology; D035964:Oxocins; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012110:Reserpine / Q000494:pharmacology*; D000095702:Polyether Toxins
chemical_list: D000001:Calcimycin; D002118:Calcium; D002121:Calcium Channel Blockers; D005711:Gallopamil; D007473:Ion Channels; D008387:Marine Toxins; D035964:Oxocins; D012110:Reserpine; C020394:maitotoxin; D000095702:Polyether Toxins