Author/Editor		Mason, WT; Rawlings, SR; Cobbett, P; Sikdar, SK; Zorec, R; Akerman, SN; Benham, CD; Berridge, MJ; Cheek, T; Moreton, RB
Title		Control of secretion in anterior pituitary cells - linking ion channels, messengers and exocytosis
Type		članek
Source		J Exp Biol
Vol. and No.		Letnik 139
Publication year		1988
Volume		str. 287-316
Language		eng
Abstract		Normal anterior pituitary cells, in their diversity and heterogeneity, provide a rich source of models for secretory function. However, until recently they have largely been neglected in favour of neoplastic, clonal tumour cell lines of pituitary origin, which have enabled a number of studies on supposedly homogeneous cell types. Because many of these lines appear to lack key peptide and neurotransmitter receptors, as well as being degranulated with accompanying abnormal levels of secretion, we have developed a range of normal primary anterior pituitary cell cultures using dispersion and enrichment techniques. By studying lactotrophs, somatotrophs and gonadotrophs we have revealed a number of possible transduction mechanisms by which receptors for hypothalamic peptides and neurotransmitters may control secretion. In particular, the transduction events controlling secretion from pituitary cells may differ fundamentally from those found in other cell types. Patch-clamp recordings in these various pituitary cell preparations have revealed substantial populations of voltage-dependent Na+, Ca2+ and K+ channels which may support action potentials in these cells. Although activation of these channels may gate Ca2+ entry to the cells under some conditions, our evidence taken with that of other laboratories suggests that peptide-receptor interactions leading to hormone secretion occur independently of significant membrane depolarization. Rather, secretion of hormone and rises in intracellular calcium measured with new probes for intracellular calcium activity, can occur in response to hypothalamic peptide activation in the absence of substantial changes in membrane potential. These changes in intracellular calcium activity almost certainly depend on both intracellular and extracellular calcium sources.(trunc.)
Descriptors		EXOCYTOSIS ION CHANNELS PITUITARY GLAND, ANTERIOR SECOND MESSENGER SYSTEMS CALCIUM CYCLIC AMP CYCLIC GMP ELECTROPHYSIOLOGY PHOSPHATIDYLINOSITOLS