AJP - Cell Physiology, Vol 259, Issue 3 C515-C520, Copyright © 1990 by American Physiological Society
Gadolinium blocks low- and high-threshold calcium currents in pituitary cells
B. A. Biagi and J. J. Enyeart
Department of Physiology, Ohio State University, Columbus 43210.
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.
