P2Y2 receptor activation opens pannexin‐1 channels in rat carotid body type II cells: potential role in amplifying the neurotransmitter ATP

Carotid body (CB) chemoreceptor complexes consist of receptor type I cells, intimately associated with glia‐like type II cells whose function is poorly understood. We show that type II cells in the rat CB express gap junction‐like proteins, pannexin‐1 (Panx‐1) channels, which form non‐selective pores permeable to ions and large molecules such as ATP, a key CB neurotransmitter. Activation of purinergic P2Y2 receptors on type II cells led to a rise in intracellular Ca2+, and a prolonged membrane depolarization due to opening of Panx‐1 channels. In a CB co‐culture model, where purinergic P2X2/3‐expressing petrosal neurones served as a reporter or biosensor of ATP release, we show that selective activation of P2Y2 receptors on type II cells can lead to ATP release via Panx‐1 channels. We propose that type II cells may function as amplifiers of the neurotransmitter ATP during chemotransduction, via the mechanism of ATP‐induced ATP release.