POTASSIUM INTAKE AND CARDIOVASCULAR REACTIVITY IN CHILDREN WITH RISK-FACTORS FOR ESSENTIAL-HYPERTENSION

Objectives: Our study objectives were as follows: (1) to determine whe ther urinary excretion of potassium is lower in black than in white ch ildren, (2) to determine whether cardiovascular reactivity (CVR) varie s inversely with dietary intake of potassium, and (3) to confirm that CVR is greater in black than in while children, and in children with a family history of hypertension than in those without such a history. Study design: Baseline measurements included 24-hour urinary sodium, p otassium, and creatinine levels and food intake (by questionnaire). Re sting and stress blood pressures were measured during blood sampling, cold water foot immersion, and a video game before and after 1 week ea ch of supplementation with potassium citrate, 1.5 mmol/kg per day, and placebo administered in random order. Results: Thirty-nine children a ged 7 to 15 years were studied. White subjects had higher baseline exc retion of potassium than black subjects (p < 0.001) and higher vegetab le intake (p < 0.01), which were positively correlated (r = 0.53, p < 0.001). At baseline, the 24-hour urinary potassium/creatinine ratio va ried inversely with diastolic CVR to the video game stressor in white children (r = -0.55, p = 0.02). Cardiovascular reactivity was not atte nuated measurably by potassium supplementation compared with placebo. The CVR was greater in children with a family history of hypertension than in those without, but nas not greater in black children than in w hite children. Conclusions: The urinary potassium/creatinine ratio is higher in white than black children because their intake of vegetables is greater; dietary potassium intake may modulate CVR, particularly i n white children with a family history of hypertension, but magi need to be supplemented for more than 1 week to demonstrate attenuation of CVR; and a family history of hypertension may be a stronger predictor of enhanced CVR than is race.