Rapid metabolism of exogenous angiotensin II by catecholaminergic neuronal cells in culture media

• Published in: Physiological reports 2015-02, Vol.3 (2), p.e12287-n/a
• Main Authors: Basu, Urmi, Seravalli, Javier, Madayiputhiya, Nandakumar, Adamec, Jiri, Case, Adam J., Zimmerman, Matthew C.
• Format: Article
• Language: English
• Subjects: Angiotensin; Angiotensin II; angiotensin peptides; Blood pressure; Brain; Cardiovascular diseases; Cardiovascular system; CATH.a neurons; Cell culture; Chromatography; Congestive heart failure; Culture media; Heart failure; Hypertension; Kinases; Liquid chromatography; liquid chromatography‐tandem mass spectrometry; Mass spectrometry; Mass spectroscopy; Metabolites; neuronal cell culture models; Neurons; Original Research; Pathogenesis; Peptides; Physiology; Scientific imaging; Studies; Therapeutic applications; Transcription factors
• ISSN: 2051-817X; 2051-817X
• DOI: 10.14814/phy2.12287

Angiotensin II (AngII) acts on central neurons to increase neuronal firing and induce sympathoexcitation, which contribute to the pathogenesis of cardiovascular diseases including hypertension and heart failure. Numerous studies have examined the precise AngII‐induced intraneuronal signaling mechanism in an attempt to identify new therapeutic targets for these diseases. Considering the technical challenges in studying specific intraneuronal signaling pathways in vivo, especially in the cardiovascular control brain regions, most studies have relied on neuronal cell culture models. However, there are numerous limitations in using cell culture models to study AngII intraneuronal signaling, including the lack of evidence indicating the stability of AngII in culture media. Herein, we tested the hypothesis that exogenous AngII is rapidly metabolized in neuronal cell culture media. Using liquid chromatography‐tandem mass spectrometry, we measured levels of AngII and its metabolites, Ang III, Ang IV, and Ang‐1‐7, in neuronal cell culture media after administration of exogenous AngII (100 nmol/L) to a neuronal cell culture model (CATH.a neurons). AngII levels rapidly declined in the media, returning to near baseline levels within 3 h of administration. Additionally, levels of Ang III and Ang‐1‐7 acutely increased, while levels of Ang IV remained unchanged. Replenishing the media with exogenous AngII every 3 h for 24 h resulted in a consistent and significant increase in AngII levels for the duration of the treatment period. These data indicate that AngII is rapidly metabolized in neuronal cell culture media, and replenishing the media at least every 3 h is needed to sustain chronically elevated levels. e12287 Our results demonstrate that a single exogenous administration of AngII to CATH.a neurons in culture does not result in chronically elevated levels of AngII in the media. Additionally, our data show that giving fresh AngII (100 nmol/L) every 3 h to cultured CATH.a neurons does indeed keep levels of AngII in the media significantly elevated for at least 24 h. We speculate that establishing cell culture models with chronically elevated levels of AngII will improve our understanding of AngII intracellular signaling pathways, not only in neuronal cultures, but in other cell types as well.