title: Sodium-lithium countertransport activity is decreased after weight loss in healthy obese men.
abstract: Maximal red blood cell (RBC) sodium-lithium countertransport activity has been consistently related to essential hypertension and may be a marker for risk of developing hypertension. Although there is strong evidence for genetic control of sodium-lithium countertransport, increasing evidence suggests that obesity and insulin-glucose metabolism are related to countertransport activity. This study was performed to determine whether countertransport activity decreases with weight loss in healthy obese adults. Forty-five healthy, white, obese adults were studied at baseline and after 6 months of behavioral dietary intervention. Weight loss was 11.5 kg (25.4 lb) in 24 men and 8.1 kg (17.8 lb) in 21 women. Sodium-lithium countertransport activity decreased 55.0 mumol Li/L RBC/h in men (P < .001, paired t test) and 14.6 mumol Li/L RBC/h in women (NS). Change in countertransport activity was correlated with change in body mass index (BMI) in men (r = .52, P < .01) and women (r = .27, NS) and was also strongly correlated with change in fasting glucose levels in both men and women (r = .50 and r = .56, respectively; P < .01) and with change in fasting insulin levels in men (r = .42, P = .04). Change in countertransport activity was not significantly related to change in physical exercise or serum lipid levels. There was a large decrease in systolic blood pressure in men (10.0 mm Hg, P < .001) and a smaller decrease in women (4.1 mm Hg, P < .05). These changes were significantly correlated with change in weight, but not with change in countertransport or baseline countertransport activity.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, PA.
authors.forename: C H
authors.initials: CH
authors.lastname: Bunker
authors.forename: R R
authors.initials: RR
authors.lastname: Wing
authors.forename: D J
authors.initials: DJ
authors.lastname: Becker
authors.forename: L H
authors.initials: LH
authors.lastname: Kuller
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D017920:Antiporters; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002352:Carrier Proteins / Q000502:physiology*; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D013997:Time Factors; D015431:Weight Loss / Q000502:physiology*
chemical_list: D017920:Antiporters; D001786:Blood Glucose; D002352:Carrier Proteins; D007328:Insulin; C045885:sodium-lithium countertransporter; D005947:Glucose