Unstimulated Salivary Secretion and Heart Rate Variability in Healthy Subjects

Abstract

Background. Unstimulated salivary flow rate (USFR) has a close relationship with the sympatheticparasympathetic activities of the autonomic nervous system (ANS). The heart rate variability (HRV) allows knowing the balance between the sympathetic and parasympathetic activities of the ANS. Objective: The objective of this work was to examine the relationship between USFR and the balance of sympathetic and parasympathetic activities of the ANS assessed by measuring HRV. Materials and Methods: Fifty-six healthy subjects were studied divided into two groups according to a higher level (A) or lower (B) USFR. The USFR and the VFC were measured consecutively. The Pearson correlations of the variables of the intensity and frequency domains of the HRV with the values of the USFR of the whole group and either the groups with smaller or higher USFR were calculated. Values with p< 0.05 were considered statistically significant. Results: The USFR of subjects with lower USFR correlated positively and significantly with PNN50 (p< 0.001), RMSSD (p< 0.001) and HF (p= 0.0183); and in a negative and significant way with the LF (p= 0.0182); while in the subjects of the total group and the group with higher USFR, it did not correlate significantly with the HRV parameters. Conclusions: The results obtained allow us to propose that in healthy subjects with lower USFR, the sympathetic-parasympathetic activity relationship of the ANS plays a critical role in the control of USFR; while in subjects with greater USFR, other factors may have a role preponderant.