Reserpine is a calcium channel antagonist in normal and GH3 rat pituitary cells.
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.
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Judd
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Yasumoto
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MacLeod
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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
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