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Participation of transient‐type Ca 2+ channels in the sustained increase of Ca 2+ level in GH 3 cells
Author(s) -
Suzuki Nobuyuki,
Kano Masaakira,
Tanakadate Akihiro,
Kudo Yoshihisa,
Takagi Hiroshi,
Yoshioka Tohru
Publication year - 1990
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041440109
Subject(s) - chemistry , endocrinology , medicine , channel blocker , biophysics , thyrotropin releasing hormone , cytosol , voltage dependent calcium channel , patch clamp , calcium , fura 2 , hormone , biochemistry , biology , receptor , enzyme
Participation of two types of Ca 2+ channels (T‐ and L‐types) in the sustained increase of cytosolic‐free Ca 2+ concentration ([Ca 2+ ] i ) was studied in thyrotropin‐releasing hormone (TRH)‐stimulated clonal GH 3 pituitary cells. The effects of Ca 2+ channel blockers were analyzed by measuring Ca 2+ channel current and [Ca 2+ ] i , using whole‐cell voltage‐clamp and Fura‐2 fluorometry, respectively. Phenytoin (100 μM) and Ni 2+ (100 μM) selectively blocked T‐type Ca 2+ channels and suppressed the TRH‐induced sustained [Ca 2+ ] i increase in single cells. Synthetic ω‐conotoxin (ω‐CgTX, 2 μM) preferentially blocked L‐type Ca 2+ channels, but it did not suppress the TRH‐induced sustained [Ca 2+ ] i increase. The present results suggest that the sustained elevations of [Ca 2+ ] i triggered by TRH may be mediated by T‐type Ca 2+ channels in GH 3 cells.