US EPA

9208631 

Journal Article 

Activin A increases cytosolic free calcium concentration in rat pituitary somatotropes 

Tasaka, K; Kasahara, K; Masumoto, N; Mizuki, J; Kurachi, H; Miyake, A; Tanizawa, O; , 

1992 

Yes 

Biochemical and Biophysical Research Communications
ISSN: 0006-291X
EISSN: 1090-2104 

ACADEMIC PRESS INC JNL-COMP SUBSCRIPTIONS 

SAN DIEGO 

974-980 

English 

1627148 

WOS:A1992JB54100026 

The effect of activin A on the cytosolic free calcium concentration ([Ca2+]i) in normal rat pituitary cells was examined using a calcium sensitive fluorescent dye, indo 1 AM, and a digital imaging fluorescent microscope system. The cells showing an increase in [Ca2+]i in response to activin A were then characterized by comparison with cells responding to growth hormone releasing hormone (GRH), thyrotropin releasing hormone (TRH), corticotropin releasing hormone (CRH), and gonadotropin releasing hormone (GnRH) in monolayer cultures of normal rat pituitary cells. Activin A increased [Ca2+]i in some cells in a mixed population of normal rat pituitary cells. The cells that responded to activin A also responded to GRH. Most of these cells were not affected by other tropic hormones (CRH, TRH, and GnRH), but a few cells responded to both GRH and TRH. None of the activin A-responding cells responded to CRH or GnRH, and none of the CRH- or GnRH-responding cells responded to activin A. In a preparation of somatotropes purified 80-90% by fluorescence-activated cell sorting, activin A increased [Ca2+]i in 30% of the cells that shows a [Ca2+]i-response to GRH. These findings suggest direct involvement of somatotropes in activin A-induced biological events in the rat pituitary gland.