Functional Roles of Anion Exchangers in Primary Sensory Neurons

by Garzon-Muvdi, Tomas

Primary Sensory Neurons (PSNs) convey all somatic and visceral information to the spinal cord and brain stem. Unlike mature central neurons, PSNs are depolarized by GABA throughout adulthood; they maintain their Cl- above electrochemical equilibrium throughout the entire cell surface. At the central terminals it makes possible primary afferent depolarization (PAD) produced by GABA released from interneurons. PAD plays a major role in presynaptic inhibition, a key mechanism in controlling flow of somatosensory information. The present study shows that PSNs innervating muscle spindles, Golgi tendon organs and low threshold cutaneous mechanoreceptors express an Anion Exchanger (AE) mechanism functionally coupled to Carbonic Anhydrases (CA). We proposed that the AE regulates intracellular pH and together with Na+, K+, 2Cl- cotransport maintains [Cl-] above equilibrium in these neurons. Molecular methods suggest that the AE may be AE3, which may be coupled to intracellular CAII and extracellular CAIV or CAXIV forming a transport metabolon.