The relationship of erythrocyte sodium-lithium countertransport to blood pressure and metabolic abnormalities in a sample of untreated middle-aged male workers

Objectives: To investigate the relationship between erythrocyte sodium-lithium countertransport and blood pressure in a randomly selected sample of untreated male workers and to evaluate the influence of a set of metabolic abnormalities commonly associated with hypertension on this relationship. Design: A cross-sectional investigation of a randomly selected sample of untreated male workers (n = 216, age range 21-59 years) at the Olivetti factory in Pozzuoli, Naples. Methods: Standardized measurements of anthropometric and metabolic parameters, blood pressure and Na⁺ Li⁺ countertransport were performed. Results: In a simple linear correlation analysis Na⁺ Li⁺ countertransport was directly related to plasma triglycerides and uric acid concentrations, body mass index (BMI) and systolic and diastolic blood pressure. Significantly higher values of Na⁺ Li ⁺countertransport were observed in the two upper quintiles of the serum triglycerides and uric acid distributions, and of the BMI distribution. Na⁺ Li⁺ countertransport accounted for approximately 2% of the blood pressure variation in this study population, but its contribution to the effect of metabolic covariates was not statistically significant. Hypertensive individuals with one or more metabolic abnormality had a significantly higher mean level of Na⁺ Li⁺ countertransport than those hypertensives who were free of such alterations. Conclusions: The results of the present study suggest that a high level of Na⁺ Li⁺ countertransport is more common in those hypertensive individuals who have concomitant metabolic abnormalities than in hypertensives who are free of such abnormalities.