Neurogenic substance P—influences on action potential production in afferent neurons of the kidney?

Language
en
Document Type
Article
Issue Date
2023-03-30
First published
2021-04-01
Issue Year
2021
Authors
Rodionova, Kristina
Hilgers, Karl F.
Linz, Peter
Schätzl, Johannes
Raschke, Giulia
Ott, Christian
Schmieder, Roland E.
Schiffer, Mario
Amann, Kerstin
Veelken, Roland
Editor
Publisher
Springer Berlin Heidelberg
Abstract

We recently showed that a substance P (SP)–dependent sympatho-inhibitory mechanism via afferent renal nerves is impaired in mesangioproliferative nephritis. Therefore, we tested the hypothesis that SP released from renal afferents inhibits the action potential (AP) production in their dorsal root ganglion (DRG) neurons. Cultured DRG neurons (Th11-L2) were investigated in current clamp mode to assess AP generation during both TRPV1 stimulation by protons (pH 6) and current injections with and without exposure to SP (0.5 µmol) or CGRP (0.5 µmol). Neurons were classified as tonic (sustained AP generation) or phasic (≤ 4 APs) upon current injection; voltage clamp experiments were performed for the investigation of TRPV1-mediated inward currents due to proton stimulation. Superfusion of renal neurons with protons and SP increased the number of action potentials in tonic neurons (9.6 ± 5 APs/10 s vs. 16.9 ± 6.1 APs/10 s, P < 0.05, mean ± SD, n = 7), while current injections with SP decreased it (15.2 ± 6 APs/600 ms vs. 10.2 ± 8 APs/600 ms, P < 0.05, mean ± SD, n = 29). Addition of SP significantly reduced acid-induced TRPV1-mediated currents in renal tonic neurons (− 518 ± 743 pA due to pH 6 superfusion vs. − 82 ± 50 pA due to pH 6 with SP superfusion). In conclusion, SP increased action potential production via a TRPV1-dependent mechanism in acid-sensitive renal neurons. On the other hand, current injection in the presence of SP led to decreased action potential production. Thus, the peptide SP modulates signaling pathways in renal neurons in an unexpected manner leading to both stimulation and inhibition of renal neuronal activity in different (e.g., acidic) environmental contexts.

Journal Title
Pflügers Archiv - European Journal of Physiology
Volume
473
Issue
4
Citation
Pflügers Archiv - European Journal of Physiology 473.4 (2021): S. 633-646. <https://link.springer.com/article/10.1007/s00424-021-02552-z>
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