Calcium channel and prolactin release in rat clonal pituitary cells: effects of verapamil
Ozawa, S.; Kimura, N.
American Journal of Physiology 243(1): E68-E73
1982
ISSN/ISBN: 0002-9513 PMID: 6283913 Document Number: 187825
Effects of verapamil on membrane electrical properties and prolactin cell line GH3. TRH, Ba2+ and high concentration of K+ enhance the release of PRL from GH3 cells. These stimulatory actions on PRL release were inhibited by adding 10-4 M verapamil to the bathing mediums. The maximum rate of rise of the Ca action potential was reduced to 17% of the control by addition of 10-4 M verapamil. Ba2+ caused a sustained membrane depolarization because Ba2+ goes through the Ca channels and blocks the development of the delayed rectification. This effect of Ba2+ was also inhibited by verapamil. Verapamil suppressed both the Na+ and outward K+ currents in addition to the Ca2+ current. The suppressive effect of verapamil on the voltage-sensitive Ca current is probably responsible for the inhibition of TRH- and high K+-stimulated PRL released because the suppression of the Na+ and outward K+ currents does not inhibit the stimulatory actions of these secretagogues.