SODIUM-LITHIUM COUNTERTRANSPORT AND BLOOD-PRESSURE - LONGITUDINAL FINDINGS

A significant and positive association between red blood cell sodium l ithium countertransport (Na-Li CT) and blood pressure has been found i n numerous studies. However, the majority of the studies presented to date are cross-sectional in nature and limited information exists on t he longitudinal association between Na-Li CT and blood pressure. The p resent study analyzes the longitudinal association between Na-Li CT an d blood pressure in 124 men participants in the Olivetti Heart Study a nd normotensives at the baseline examination. The Na-Li CT measured at the 12 year follow-up examination was analyzed in regard to the blood pressure changes over time during the 12 year follow-up. Na-Li CT (me asured at follow-up examination) was positively related to changes ove r time in systolic pressure (r = 0.16) and diastolic pressure (r = 0.0 7) and changes in body mass index (r = 0.18). When blood pressure chan ges over time were analyzed by tertiles of Na-Li CT, the highest terti le group exhibited on the average significantly higher increases in sy stolic blood pressure compared with participants of the lowest tertile of the Na-Li CT distribution, This difference remained statistically significant after adjusting for the changes in weight observed during the 12 years follow-up. These findings indicate that the Na-Li CT dist ribution is related to blood pressure changes over time. However, the usefulness of Na-Li CT as a predictor of incidence of hypertension rem ains to be established.