Endothelin-1 enhanced carotid body chemosensory activity in chronic intermittent hypoxia through PLC, PKC and p38MAPK signaling pathways.

Endothelin-1 (ET-1), as it functions as a neuromodulator, has been associated with hypertension in chronic intermittent hypoxia (CIH) which attribute to enhanced carotid body sensibility to hypoxia. However, the molecular mechanism of ET-1 on carotid body sensibility in CIH is still not clear. Here, effect of ET-1 on carotid body chemosensory stimulation in rats exposed to either CIH or room air (Normoxia) was explored. Furthermore, Phospholipase C (PLC), Protein kinase C (PKC) or p38 MAPK antagonists were adopted to clarify the signalling pathways involved. Results showed that ET-1 induced a higher increase of carotid sinus nerve activity (CSNA) in animals exposed to CIH. Both ETA and ETB receptor expression were up-regulated by CIH exposure, but only ETA is responsible for ET-1 induced CSNA increase. Additional, the increase was inhibited by PLC, PKC, p38 MAPK antagonists and calcium channel blocker. Our findings support that ETA receptor mediates ET-1-induced CSNA increase through PLC, PKC and p38 MAPK signalling pathways in chronic intermittent hypoxia. Also, our study indicated that calcium influx was necessary for enhancing effect of ET-1 on CSNA.