Kv2 channels contribute to neuronal activity within the vagal afferent-nTS reflex arc

Am J Physiol Cell Physiol. 2023 Nov 20. doi: 10.1152/ajpcell.00366.2023. Online ahead of print.ABSTRACTDiversity in the functional expression of ion channels contributes to the unique patterns of activity generated in visceral sensory A-type myelinated neurons versus C-type unmyelinated neurons in response to their natural stimuli. In the present study, Kv2 channels were identified as underlying a previously uncharacterized delayed rectifying potassium current expressed in both A- and C- type nodose ganglion neurons. Kv2.1 and 2.2 appear confined to the soma and initial segment of these sensory neurons, however, neither was identified in their central presynaptic terminals projecting onto relay neurons in the nucleus of the solitary tract (nTS). Kv2.1 and Kv2.2 were also not detected in the peripheral axons and sensory terminals in the aortic arch. Functionally, in nodose neuron somas Kv2 currents exhibited frequency dependent current inactivation and contributed to action potential repolarization in C-type neurons but not A-type neurons. Within the nTS, block of Kv2 currents does not influence afferent presynaptic calcium influx or glutamate release in response to afferent activation, supporting our immunohistochemical observations. On the other hand, Kv2 channels contribute to membrane hyperpolarization and limit action potential discharge rate in second-order neurons. Together, these data demonstrate Kv2 channels influence neuronal discharge within the vagal afferent - nTS...
Source: American Journal of Physiology. Cell Physiology - Category: Cytology Authors: Source Type: research