Measurement of changes in cellular calcium metabolism in response to thyrotropin-releasing hormone

Abstract

Publisher Summary Elevation of the concentration of free calcium ion in the cytoplasm of cells ([Ca 2+ ] i ) is an early event following the binding of many stimuli to plasma membrane receptors. The free (or ionized) calcium then plays an important role as a coupling factor leading to the activation of the final cellular response (“stimulus-response coupling”). The elevation of [Ca 2+ ] i is caused by the mobilization (or redistribution) of cellular calcium, enhanced influx of extracellular Ca 2+ , inhibition of the efflux of intracellular calcium, or a combination of these processes. The chapter describes the methods that can be employed to study these various aspects of cellular calcium homeostasis, including the direct measurement of [Ca 2+ ] i . It discusses studies of two pituitary cell types in vitro ––mammotropic (GH3) and thyrotropic (TtT) cells in culture. The examples presented to illustrate the use of these methods are from studies that attempt to define the mechanism of the action of thyrotropin releasing hormone (TRH) in these two cell types.