Aging related changes in mixed basal saliva concentration of sodium, potassium and chloride in healthy non medicated humans

It is well known that the salivary flow is reduced by aging but ionic composition changes associated to aging have been less evaluated. To measure salivary and plasmatic [Na(+)], [K(+)] and [Cl(-)] and to correlate with age in healthy, non-medicated subjects of any gender, 165 healthy participating subjects (over 15 years old) were asked to give sample of 5 mL mix basal saliva in a plastic vial without any stimulation technique, additionally, 5 mL of venous blood was collected. Samples [Na(+)] and [K(+)] were measured by flame photometry (Corning™ M-405) and [Cl(-)] by voltametric chlorometry (Corning™ M-920). Ionic concentrations were expressed as (X±DE; meq.L⁻¹). All three ionic concentrations progressively increased with age, with the lineal regression equation being: [Na(+)] mEq=17.76 + 0.26(Age); r=+0.42; F=31.5; P=0.00001; [K(+)] mEq=13.2+0.15(Age); r=+0.32; F=16.5; P=0.00001; [Cl(-)] mEq=9.05+0.18(Age); r=+0.35; F=7.8; P=0.0071. Age induced changes in salivary ionic concentrations were not associated to blood ionic changes. However, saliva and blood [Na(+)] and [K(+)] were correlated (r=+0.25; F=4.49; P=0.04 and r=+0.30; F=6.98; P=0.01, respectively). Significant association was found among salivary ions: [Na(+)] mEq=9.14+0.99[K(+)] (r=+0.79; F=95.2; P=0.000001); [Cl(-)] mEq=0.95+0.56[Na(+)] (r=0.79; F=106.6; P=0.000001) and [Cl(-)] mEq=3.45+0.69[K(+)] (r=0.73; F=72.5; P=0.000001). These results confirm and measure the impact of aging over the mixed and resting salivary secretion process and suggest that local changes are not related to blood ionic composition.