Endogenous salivary citrate is associated with enhanced rheological properties following oral capsaicin-stimulation

Alexander Gardner, Po-Wah So (Lead / Corresponding author), Guy Carpenter

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)
146 Downloads (Pure)


Saliva displays viscoelastic properties which enable coating, lubrication and protection of the oral mucosa and hard tissues. Individuals lacking saliva or perceiving oral dryness can manage their symptoms using artificial saliva preparations, but these often fail to mimic the sensation and functionality of natural saliva. It is widely acknowledged that mucins (MUC7 and MUC5B) confer saliva's rheological properties, but artificial saliva containing purified mucins is still often an inadequate substitute. This work aimed to explore salivary components that influence salivary extensional rheology to better understand how natural saliva could be replicated. Saliva was stimulated via control and capsaicin solutions in healthy volunteers. Extensional rheology was analysed using a CaBER‐1 (capillary breakup) extensional rheometer. Protein composition, including mucins, was measured by gel‐electrophoresis band densitometry and metabolites were measured by 1H nuclear magnetic resonance spectroscopy. Capsaicin stimulation significantly increased capillary breakup time, extensional viscosity and the abundance of most major salivary proteins. Stimulation also increased salivary citrate and choline concentrations. Significant correlations were found between capillary breakup time and amylase (r = 0.67, P < 0.05), statherin (ρ = 0.66, P < 0.05) and citrate (ρ = 0.81, P < 0.01). The relationship between citrate and salivary rheology was subsequently investigated in vitro. These results suggest that citrate and non‐mucin proteins are stronger predictors of salivary rheology than the more often studied mucin glycoproteins. Potential mechanisms are discussed and future work in this area could help formulate more effective saliva substitutes, more closely resembling natural saliva.
Original languageEnglish
Pages (from-to)96-107
Number of pages12
JournalExperimental Physiology
Issue number1
Early online date8 Nov 2019
Publication statusPublished - 1 Jan 2020


  • metabolomics
  • rheology
  • saliva

ASJC Scopus subject areas

  • Physiology (medical)
  • Nutrition and Dietetics
  • Physiology


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