Expression and Localization of Acid‐Sensing Ion Channels in Mouse Nodose Ganglia

Abstract

Transduction of mechanosensation and chemosensation in sensory neurons may be mediated by various subunits of the ASIC (acid-sensing ion channel) family. We and others have experimental data to suggest that ASIC2 subunits may be more mechanosensitive whereas ASIC1 and ASIC3 may be more proton sensitive. The expression of various ASIC subunits has been reported in DRG neurons. Because of our interest in cardiovascular sensory signals we used quantitative PCR to evaluate the mRNA expression of ASIC subunits in nodose ganglia of adult mice (n = 5). These ganglia contain the soma of vagal sensory nerves including cardiopulmonary and aortic baroreceptor afferents. The results (Fig. A) show similar relative mRNA levels for four subunits (ASIC1a, 1b, 2a and 3) with higher expression of ASIC2b subunits. In ASIC2 deficient mice the mRNA expression of other subunits was not altered significantly (Fig. B). Specific antibodies were used in the immunohistochemical assay to determine the locations of ASIC proteins. The colocalization of ASIC1, 2 and 3 subunits was observed in the same nodose neurons, supporting the heteromultimeric model of ASIC channels. It is also possible that specific subunits may target selectively the mechanosensitive versus proton sensitive nerve endings from the same neuron. These results provide the basis for evaluating changes in expression of various subunits in pathologic states. (HL14388)