Kidney Week

Abstract: FR-PO321

Stimulatory Effects of NaCl on Tonic Highly Sensitive Cultured Neurons with Renal Afferents

Session Information

• Hypertension and CVD: Mechanisms - I
  October 26, 2018 | Location: Exhibit Hall, San Diego Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Hypertension and CVD

• 1403 Hypertension and CVD: Mechanisms

Authors

• Rodionova, Kristina, Dept. of Nephrology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Kristina Rodionova,

• Dietz, Amelie, Dept. of Nephrology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Amelie Dietz,

• Hindermann, Martin, Dept. of Nephrology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Martin Hindermann,

• Ditting, Tilmann, Dept. of Nephrology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Tilmann Ditting,

• Ott, Christian, Dept. of Nephrology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Christian Ott,

• Schmieder, Roland E., Dept. of Nephrology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Roland E. Schmieder,

• Amann, Kerstin U., Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Kerstin U. Amann,

• Veelken, Roland, Dept. of Nephrology, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany

Roland Veelken,

Background

An important regulatory role of afferent nerve fibers from the kidney has been postulated for a while especially in developing hypertension and counterregulation of salt loading. However, it is not known how salt will act on renal afferent nerves. Hence we wanted to test the hypothesis that even short exposure to low NaCl concentrations will already induce significant action potential generation in cultured neurons with renal axons.

Methods

Over 180 cultured dorsal root ganglion neurons (Th11-L2) of rats with renal afferents in vitro were investigated in current clamp mode to asses action potential (AP) generation and classify neurons as tonic (high AP generation upon stimulation) and phasic (AP < 5 upon stimulation). Furthermore, experiments in voltage clamp mode to assess inward currents have been performed. Cultured neurons were exposed to short periods of superfused boli with increasing NaCl concentrations (0.3%, 3%, 4.5%, 10%).

Results

Renal neurons exhibited significant production of action potentials to NaCl superperfusion that was impaired with increasing concentrations of NaCl (0.3%: 36+/-9.6 APs/10s; 3%: 14.5+/-3.6 APs/10s; 4.5%: 7.8+/-0.7 APs/10s; p<0.05; mean+/-SEM). Superfusion with 10 % NaCl increased AP generation in tonic neurons (15.9+/-3.1 APs/10s, p<0.05; mean+/-SEM) likely due to unspecific e.g. osmotic effects. Phasic neurons were not affected by NaCl. Classification of renal neurons according to their firing pattern (tonic or phasic) revealed the majority of renal neurons to be tonic as previously described.

Conclusion

Superfusion with NaCl in a low concentration led to marked increases of action potential production in tonic, highly active neurons (a characteristic feature of renal innervation) that was impaired with higher superpefused NaCl concentrations in a dose-dependent manner. Hence, NaCl likely influences renal sympathetic nerve activity via the stimulation of renal afferents. However, this effect might be not uniform for all forms and stages of salt loading and hypertension.

Funding

• Clinical Revenue Support