Evidence that 5‐HT stimulates intracellular Ca2+ signalling and activates pannexin‐1 currents in type II cells of the rat carotid body

摘要

Key points class="unordered" style="list-style-type:disc" id="tjp12347-list-0001">5‐HT is a neuromodulator released from carotid body (CB) chemoreceptor (type I) cells and facilitates the sensory discharge following chronic intermittent hypoxia (CIH).In the present study, we show that, in addition to type I cells, adjacent glial‐like type II cells express functional, ketanserin‐sensitive 5‐HT2 receptors, and their stimulation increases cytoplasmic Ca²⁺ derived from intracellular stores.In type II cells, 5‐HT activated a ketanserin‐sensitive inward current (I 5‐HT) that was similar to that (I UTP) activated by the P2Y2R agonist, UTP.As previously shown for I UTP, I 5‐HT was inhibited by BAPTA‐AM and carbenoxolone (5 μm), a putative blocker of ATP‐permeable pannexin (Panx)‐1 channels; I UTP was reversibly inhibited by the specific Panx‐1 mimetic peptide channel blocker, ¹⁰Panx peptide.Paracrine stimulation of type II cells by 5‐HT, leading to ATP release via Panx‐1 channels, may contribute to CB excitability, especially in pathophysiological conditions associated with CIH (e.g. obstructive sleep apnoea).