Acetylcholine-induced calcium signalling in adrenaline and noradrenaline-containing adrenal chromaffin cells

摘要

Adrenal chromaffin cells secrete catecholamines in response to cholinergic receptor activation by acetylcholine (ACh). Characteristics of Ca2+ transients induced by activation of nicotinic (nAChRs) and muscarinic (mAChRs) receptors were analyzed using Fura-2 fluorescent measurements on rat chromaffin cells. We first found two populations of chrornaffin cells, which differently responded on AChR stimulation. In the first group (n-cells), consecutive ACh applications evoked persistent Ca2+ transients, whereas desensitizing transients were observed in the other group (m-cells). The AChR agonists and antagonists precisely imitated or abolished the ACh action on n- and m-type cells, respectively. Cytochemical staining showed that n-cells contained adrenaline, whereas m-cells-noradrenaline. Thus, for the first time we found that nAChRs and mAChRs are differentially expressed in adrenergic and noradrenergic chrornaffin cells, respectively. Our data suppose that chrornaffin cells can be differentially regulated by incoming ACh signals and in such way release different substances-adrenaline and noradrenaline. (C) 2004 Elsevier Inc. All rights reserved. [References: 51]