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Electrophysiological characterization of mouse intracardiac calbindin neurons
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Edité par CCSD ; Biophysical Society -
International audience. Neural control of the heart involves central and peripheral neurons that act interdependently to modulate cardiac parameters such as heart rate, conduction velocity or contractility. Within this cardiac neuronal regulation, the intrinsic cardiac nervous system, which correspond to clusters of neurons found on the dorsal atrial surface of the heart, is receiving growing attention. Indeed, whereas they were initially considered as simple parasympathetic postganglionic neurons, studies conducted over the past 30 years suggested a more complex organization, involving the existence of sensory, local regulatory and motor neurons within intracardiac ganglia. Moreover, growing evidence suggest the implication of this neural network in the initiation and maintenance of cardiac arrhythmias. However, the functional organization of this intracardiac neural network, as well as its involvement in cardiac diseases have not been fully elucidated.Therefore, this study aims to decipher the complexity of this mouse cardiac nervous system by examining the electrophysiological properties of intracardiac neurons. The characterization of passive and active electrical membrane properties of these neurons gave rise to the identification of two distinct neuronal profiles displaying different firing characteristics. The first group was classified as phasic due to its limited firing activity while the second was defined as adapting. Phasic neurons were also characterized by a higher rheobase as well as higher AHP amplitude and duration compared to the adapting one. By using cre transgenic mice and targeted viral transduction strategy, we identified calbindin expressing neurons as a population of neurons with a distinct electrophysiological signature. This could be explained by the differential expression of several ionic channels including sodium and calcium channels and will be further investigated in the future.
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