Adaptive remodeling of rat adrenomedullary stimulus-secretion coupling in response to a chronic hypertensive environment
Résumé
Chronic elevated blood pressure impinges on the functioning of multiple organs and therefore harms body homeostasis. Elucidating the protective mechanisms whereby the organism copes with sustained or repetitive blood pressure rises is therefore a topical challenge. Here we address this issue in the adrenal medulla, the master neuroendocrine tissue involved in the secretion of catecholamines, influential hormones in blood pressure regulation. Using acute adrenal slices from spontaneously hypertensive rats, we show that chromaffin cell stimulus-secretion coupling is remodeled, resulting in a less efficient secretory function primarily upon sustained electrical or cholinergic challenges. The remodeling is supported by revamped cellular and tissular mechanisms, including chromaffin cell excitability through voltage-gated ion channel expression changes, gap junctional communication and cholinergic synaptic transmission. As such, by weakening its competence to release catecholamines, the ‘hypertensive medulla’ has elaborated an adaptive shielding mechanism against damaging effects of redundant elevated catecholamine secretion and associated blood pressure.
Mots clés
chromaffin cell excitability; cholinergic synaptic transmission; gap junctional coupling; acute adrenal slices; catecholamine assays; hypertensive rats; voltage-gated ion channels, nicotinic receptors
chromaffin cell excitability cholinergic synaptic transmission gap junctional coupling acute adrenal slices catecholamine assays hypertensive rats voltage-gated ion channels, nicotinic receptors
chromaffin cell excitability
cholinergic synaptic transmission
gap junctional coupling
acute adrenal slices
catecholamine assays
hypertensive rats
voltage-gated ion channels, nicotinic receptors
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