Trophic effects of somatostatin on calcium flux: dynamic analysis and correlation with pituitary hormone release.

ABSTRACT

Somatostatin (SRIF) modulates many aspects of normal physiology, appears useful as a potent antineoplastic agent, and may influence the development of degenerative brain disorders such as Alzheimer's disease. Regulation of cellular calcium flux by SRIF may contribute greatly to many of these interactions, yet remains controversial. SRIF rapidly causes a sustained inhibition of fractional calcium efflux from prelabeled dispersed rat pituitary cells (IC50, approximately 40 pM) and evokes a large rebound increase in efflux after the infusion, each coinciding temporally with expected physiological effects on GH release. These data support a particular role for SRIF-regulated calcium flux in the normal pulsatile pattern of GH secretion and a more general role in the varied biological actions of the peptide.