title: Gadolinium blocks low- and high-threshold calcium currents in pituitary cells.
abstract: The inhibition of L- and T-type Ca2+ currents by Gd3+ was studied in the rat pituitary GH4C1 cell line. In whole cell patch recordings, Gd3+ at concentrations of 50 nM to 5 microM blocked Ca2+ current through L-type channels. Block was promoted by prolonged channel activation. With 4.5-s test pulses to + 10 mV, Gd3+ at concentrations as low as 200 nM produced near-complete block of L current. At higher Gd3+ concentrations (5 microM), complete block occurred with short test pulses and appeared to be independent of channel activation. Gd3+ also blocked current through low-threshold T channels in GH4C1 cells. Two other trivalent elements, La3+ and Y3+, blocked L-type Ca2+ channels in GH4C1 cells with potency similar to Gd3+. These results indicate that these trivalent cations are effective nonselective inhibitors of both low- and high-threshold Ca2+ channels in endocrine cells. In this regard, they are among the most potent inorganic Ca2+ antagonists yet discovered.
authors.affiliation: Department of Physiology, Ohio State University, Columbus 43210.
authors.forename: B A
authors.initials: BA
authors.lastname: Biagi
authors.forename: J J
authors.initials: JJ
authors.lastname: Enyeart
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D004533:Egtazic Acid / Q000494:pharmacology; D005682:Gadolinium / Q000494:pharmacology*; D007700:Kinetics; D007811:Lanthanum / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D010911:Pituitary Neoplasms; D015019:Yttrium / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; D004533:Egtazic Acid; D015019:Yttrium; D007811:Lanthanum; D005682:Gadolinium; D002118:Calcium