Author/Editor		Sikdar, SK; Zorec, R; Brown, D; Mason, WT
Title		Dual effects of G-protein activation on Ca-dependent exocytosis in bovine lactotrophs
Type		članek
Source		FEBS Lett
Vol. and No.		Letnik 253, št. 1-2
Publication year		1989
Volume		str. 88-92
Language		eng
Abstract		The whole-cell patch-clamp technique was used to measure cell membrane capacitance (Cm) to monitor exocytosis in single-cultured bovine prolactin-secreting cells (lactotrophs) of the anterior pituitary. The cells were dialyzed with solutions containing different concentrations of ionised Ca and non-hydrolyzable GTP analogues (GTP-gamma-S and GMP-PNP) to activate G-proteins. We have identified two distinct effects of G-protein activation on Ca-induced exocytosis: (i) the maximum Cm increase due to intracellular Ca-dependent exocytosis was diminished, suggesting an inhibitory role of G-proteins close to the site of granule fusion, while (ii) the rate of Cm increase (delta Cm/delta t) was facilitated, revealing conversely a stimulatory role of G-proteins in the translocation of secretory granules to the fusion sites.
Descriptors		CALCIUM G-PROTEINS PITUITARY GLAND, ANTERIOR PROLACTIN CATTLE ENZYME ACTIVATION EXOCYTOSIS GUANINE NUCLEOTIDES