Okadaic acid and calyculin A enhance the effect of thyrotropin‐releasing hormone on GH3 rat anterior pituitary cells excitability

FEBS Letters

Delgado, Luis M.¹  del Camino, Donato¹  de la Peña, Pilar¹  Barros, Francisco¹ 

[1] Departamento de Biologia Funcional, Area de Bioquimica, Facultad de Medicina, Universidad de Oviedo, 3306 Oviedo, Spain

关键词: Thyrotropin-releasing hormone;    Okadaic acid;    Calyculin A;    Protein phosphatase;    Anterior pituitary;    Perforated patch;    TRH;    thyrotropin-relasing hormone;    AP;    action potential;    OKA;    okadaic acid;    CL-A;    calyculin A;    PKC;    protein kinase C;    PP;    protein phosphatse;   

DOI  :  10.1016/0014-5793(92)81362-P

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Thyrotropin-releasing hormone (TRH) causes a transient hyperpolarization followed by several minutes of increased action potential frequency in patch-perforated current-clamped GH₃ cells. Treatment of cells for 5 min with either 2 or 100 nM of the protein phosphatase inhibitor okadaic acid does not affect electrical activity of the cells, but potentiates the enhancement of action potential frequency elicited by a subsequent addition of TRH. Alternatively, 100 nM (but not 2 nM) of okadaic acid added during the second phase of TRH action, further increases the frequency of firing above that produced by the hormone. Similar effects to those of 2 nM okadaic acid are observed with 20 nM calyculin A. These data suggest that a protein phosphatase plays a major role in regulating the delayed effects of TRH on cell excitability in GH₃ cells.

【 授权许可】

Unknown