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Differential Na + –K + ‐ATPase activity in rat lemniscal and non ‐ lemniscal auditory Thalami
Author(s) -
Senatorov V. V.,
Hu Bin
Publication year - 1997
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1997.387bk.x
Subject(s) - confocal , biophysics , chemistry , membrane potential , depolarization , confocal microscopy , microbiology and biotechnology , biology , geometry , mathematics
1 Using whole‐cell recording and confocal immunofluorescent microscopy, we have investigated the differential electrogenic activity, subunit expression and subcellular distribution of the Na + –K + ‐ATPase in the lemniscal (ventral) and non‐lemniscal (dorsal) pathways of the rat medial geniculate body (MGB) in vitro.2 Bath application of Na + –K + ‐ATPase inhibitors strophanthidin or dihydroouabain produced a transient, dose‐dependent inward current or membrane depolarization which were significantly larger in dorsal MGB neurones than in ventral cells (45.9 ± 6.45 vs . 24.3 ± 4.l pA; P < 0.05 ). Electrophysiological and morphometric measurements showed that the dorsal MGB neurones had a significantly lower input conductance and a smaller somata than their ventral counterparts. The level of the resting membrane potential also differed by about 6 mV between the two cell populations, with the dorsal cells being more hyperpolarized (−74.2 ± 0.6 vs . −67.7 ± 1.3 mV; P < 0.001 ). 3 Incubation of enzymatically dissociated MGB neurones with fluorescent monoclonal antibodies against α1‐α3 isoforms of Na + –K + ‐ATPase showed that both dorsal and ventral cells expressed primarily α3 subunits. Confocal laser scanning revealed, however, that the mean pixel density of α3 fluorescent antibodies in the plasma membrane domain, but not in the cytoplasmic compartment, was about 40 % higher in dorsal neurones than in the ventral cells (29.7 ± 4.7 vs . 16.9 ± 2.3 grey shadow per pixel; P < 0.05 ). 4 The above results suggest that the electrogenic activity of the Na + –K + ‐ATPase is differentially regulated between lemniscal and non‐lemniscal auditory thalami through a mechanism that probably involves differential pump densities in the cell membrane.