Change over time in red blood cell sodium-lithium countertransport: the gubbio study

Activity of sodium-lithium countertransport (Na-Li CT) is considered a marker of a hypertension-prone condition. This study investigates changes over time in red blood cell Na-Li CT and their relation to other variables. Data collected in the Gubbio Population Study at baseline and follow-up (6-year) for people baseline ages 18-74 years (n = 2, 128) were analyzed for Na-Li CT and other variables. The average value (mean of baseline and follow-up) was used for body mass index, blood pressure, alcohol intake, plasma cholesterol, glucose, uric acid, sodium (Na), potassium (K), urinary ratio; plasma triglyceride was measured only at follow-up and included in the analysis. Analyses were controlled for sex and age. Follow-up Na-Li CT was higher than baseline (p < 0.001). Baseline Na-Li CT was directly related to follow-up Na-Li CT, and inversely to Na-Li CT change over time (p < 0.001). Baseline Na-Li CT, follow-up plasma triglyceride, and average value of body mass index, alcohol intake, plasma glucose, and plasma K related to Na-Li CT change over time in multivariate analyses (p < 0.01). With use of the median as cut-off, persons with high average value of body mass index, and alcohol intake, and plasma glucose, and with high follow-up plasma triglyceride, and with low average plasma K had an increase in Na-Li CT over follow-up greater by 43 μmol than persons with opposite characteristics (p < 0.05), although baseline Na-Li CT was higher by 114 μmol (p < 0.001). Conclusion: Na-Li CT activity reflects a metabolic condition that is related to calorie balance, alcohol intake, plasma triglyceride, glucose and K levels.