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Abstract: SA-PO327

Afferent Peptidergic Nerve Fibers: Importance for the Salt Metabolism Beyond the Kidneys?

Session Information

Category: Hypertension and CVD

  • 1403 Hypertension and CVD: Mechanisms

Authors

  • Ditting, Tilmann, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
  • Rodionova, Kristina, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
  • Ott, Christian, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
  • Schmieder, Roland E., Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
  • Schiffer, Mario, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
  • Amann, Kerstin U., Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
  • Veelken, Roland, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
Background

Sodium can be accumulated without commensurate water retention in the skin (non-osmotic sodium storage). Macrophages play a pivotal role in this context and their depletion can induce salt-sensitive hypertension. On the other hand renal afferent peptidergic nerves are involved. Since the skin is also densely innervated by afferent peptidergic nerves we hypothesized that high salt diet might enhance the release of neuropeptides from these nerve fibers

Methods

In a cross-over design, two groups of rats (n=4, each) were fed either low salt diet (LS; 0.2%) with free access to tab water for 14 days or high salt diet (HS; 8%) with free access to 0.9% saline as drinking water. After 14 days a skin sample (3x3mm) of the groin area was excised, and the diet was switched for another 14 days. Then a contralateral skin sample was taken. Tissue analyzed in an organ-bath and calcitonin gene related peptide (CGRP) content in the supernatant was measured with ELISA. After two baseline measurements within 5 min, the tissue was superfused with hypertonic saline (4.5%) for 5 min, and three further samples of the supernatant were taken every 5 min.

Results

Baseline CGRP release was similar with both diets (LS 11.9±1.5 vs HS 13.6±1.5ng/g skin). Maximum release was higher with HS diet (LS 17.5±1.8 5ng/g skin vs HS 29.8±1.3ng/g skin; *p<0.05). After diet switch the results were similar: baseline LS 9.4±1.2 ng/g skin vs HS 10.1± 1.1 ng/g skin, with HS diet the release was higher again (LS 19.7±2.1 vs HS 29.3±1.7*; *p<0.05).

Conclusion

High sodium diet sensitized neuropeptide release from peptidergic sensory nerves in the skin. Hence peptidergic afferent nerves might be an integrated body-wide system involved in sodium handling in very different target areas like skin and kidney. Putative peptidergic mechanisms (vasoregulation, chemotaxis) remain to be determined in this respect.