title: Reduced dietary potassium reversibly enhances vasopressor response to stress in African Americans.
abstract: Acute vasopressor responses to stress are adrenergically mediated and hence potentially subject to differential modulation by dietary potassium and sodium. The greater vasopressor responsiveness in blacks compared with whites might then be consequent not only to a high dietary salt intake but also to a marginally reduced dietary potassium intake. Under controlled metabolic conditions, we compared acute vasopressor responses to cold and mental stress in black and white normotensive men during three successive dietary periods: (1) while dietary potassium was reduced (30 mmol K+/70 kg per day) and salt was restricted (10 to 14 days); (2) while salt was loaded (15 to 250 mmol Na+/70 kg per day) (7 days); and (3) while salt loading was continued and potassium was either supplemented (70 mmol K+/70 kg per day) (7 to 21 days) in 9 blacks and 6 whites or continued reduced (30 mmol K+/70 kg per day) (28 days) in 4 blacks (time controls). At the lower potassium intake, cold-induced increase in forearm vascular resistance in blacks was twice that in whites during both salt restriction and salt loading. Normalization of dietary potassium attenuated cold-induced increases in both forearm vascular resistance and systolic and diastolic blood pressures in blacks but only in systolic pressure in whites. In blacks but not in whites, normalization of dietary potassium attenuated mental stress-induced increases in systolic and diastolic pressures. In normotensive blacks but not whites, a marginally reduced dietary intake of potassium reversibly enhances adrenergically mediated vasopressor responsiveness to stress. That responsiveness so enhanced over time might contribute to the pathogenesis of hypertension in blacks.
authors.affiliation: Department of Medicine, General Clinical Research Center, University of California, San Francisco, USA.
authors.forename: K
authors.initials: K
authors.lastname: Sudhir
authors.forename: A
authors.initials: A
authors.lastname: Forman
authors.forename: S L
authors.initials: SL
authors.lastname: Yi
authors.forename: J
authors.initials: J
authors.lastname: Sorof
authors.forename: O
authors.initials: O
authors.lastname: Schmidlin
authors.forename: A
authors.initials: A
authors.lastname: Sebastian
authors.forename: R C
authors.initials: RC
authors.lastname: Morris
mesh_terms: D000328:Adult; D044383:Black People; D001794:Blood Pressure / Q000502:physiology; D006801:Humans; D008297:Male; D011188:Potassium / Q000502:physiology*; D017419:Potassium, Dietary / Q000008:administration & dosage*; D013312:Stress, Physiological / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D014655:Vascular Resistance / Q000502:physiology*; D044465:White People; D001741:Black or African American
chemical_list: D017419:Potassium, Dietary; D011188:Potassium