Electrophysiological characteristics of identified kidney-related neurons in adult rat spinal cord slices.

Whole-cell patch-clamp recordings were made from kidney-related neurons in the intermediolateral cell column (IML) in horizontal slices of thoracolumbar spinal cord from adult rats. Kidney-related neurons were identified in vitro subsequent to inoculation of the kidney with a fluorescent, retrograde, transynaptic pseudorabies viral label (i.e., PRV-152). Kidney-related neurons detected in the IML expressed choline acetyltransferase, characteristic of spinal preganglionic motor neurons. Their mean resting potential was -51+/-4 mV and input resistance was 448+/-39 MOmega. Both spontaneous inhibitory and excitatory post-synaptic currents (i.e., sIPSCs and sEPSCs) were observed in all neurons. The mean frequency for sEPSCs (3.1+/-1 Hz) was approximately 2.5 times that for sIPSCs (1.4+/-0.3 Hz). Application of the glycine and GABA(A) receptor-linked Cl(-) channel blocker, picrotoxin (100 microM) blocked sIPSCs, while the ionotropic glutamate receptor antagonist, kynurenic acid (1 mM) blocked all sEPSCs, indicating they were mediated by GABA/glycine and glutamate receptors, respectively. Thus, using PRV-152 labeling allowed whole-cell patch-clamp recording of neurons in the adult spinal cord, which were kidney-related. Excitatory glutamatergic input dominated synaptic responses in these cells, the membrane characteristics of which resembled those of immature IML neurons. Combined PRV-152 pre-labeling and whole-cell patch-clamp recordings may allow more effective analysis of synaptic plasticity seen in adult models of injury or chronic disease. 2010 Elsevier Ireland Ltd. All rights reserved.