SUMMARY A population-based survey of 134 white men, recruited from the Chicago People's Gas Company labor force, was carried out to examine the association between sodium-lithium (Na-Li) countertransport and hypertension. Of the 134 participants in this industry-sponsored periodic health examination, 64 were normotensive and 70 were either taking antihypertensive medications or had a systolic pressure 3= 140 or a diastolic pressure 2= 90 mm Hg. The hypertensives were older and more overweight. Countertransport was significantly higher in hypertensives than in normotensives. Among the three subgroups of hypertensives -untreated borderline (140/90 to 160/95 mm Hg), untreated definite (over 160/95 mm Hg), and treated -an increase in countertransport was consistently observed, significant for the latter two groups. The relationship between countertransport and hypertension was independent of overweight, with countertransport being significantly related to both blood pressure and overweight. Altered ion transport may play an important role in the etiology and/or pathophysiology of hypertension. (Hypertension 5:363-367, 1983) KEY WORDS • countertransport • sodium metabolism • blood pressure R ED blood cell sodium-dependent membrane processes are currently being studied in relation to the etiology and pathogenesis of hypertension. 1 " 14 Previous case control studies have demonstrated a relationship between sodium-lithium (Na-Li) countertransport and hypertension.'-7 -15~17 This report described the results of a populationbased cross-sectional survey in employed white men relating levels of countertransport to the presence of hypertension.
Methods
Data CollectionVolunteers for this study were male employees (the great majority of whom were white) of the Chicago People's Gas Company participating in the companysponsored periodic health examination. The participation rate in this examination is over 90%. l8 During the period from June 1981 to December 1981, on a semi weekly basis, without selection the first four employees who presented at the company medical office for their regularly scheduled examination were invited to participate; response rate was 100%.A nurse measured blood pressure after the man had rested quietly in the sitting position for 5 minutes. Korotkoff sounds phases I and V were recorded from a single reading with a standard mercury sphygmomanometer. While blood was being sampled for routine laboratory analyses, an additional 15 cc of venous blood was collected in plastic tubes containing ammonium heparin. Samples were collected in the fasting state before 10 a.m. With the man in indoor clothes, with shoes off, height and weight were measured on a balance scale. Medical history was obtained through the use of a self-administered questionnaire.Of 157 white men participating in the study, 21 were excluded from this report because of a major illness (renal, hormonal, psychiatric) thought to influence intracellular ion metabolism. 6 l9 -2I In addition, two participants were excluded because of extremely...