HERITABILITY OF SALT SENSITIVITY IN BLACK-AMERICANS

Salt sensitivity is defined as a change in blood pressure in response to changes in salt and water homeostasis. Found in 73% of hypertensive and 36% of normotensive blacks, it is generally considered a hallmark of hypertension in blacks. The higher prevalence of salt sensitivity in blacks compared with whites suggests a genetic influence on this tr ait, but there is little direct evidence of heritability. We determine d the extent to which salt sensitivity is correlated in black families and estimated the heritability of this phenotype. Black families were recruited through a hypertensive proband. Both hypertensive and normo tensive adults were phenotyped with respect to salt sensitivity with a n intravenous sodium-loading, furosemide volume-depletion protocol. Sa lt sensitivity was defined as the difference between sodium-loaded and volume-depleted blood pressure. We enrolled 20 families, comprising 3 0 parent-offspring pairs and 115 adult sibling pairs, Age-adjusted fam ilial correlations ranged from .33 to .44, .19 to .37, and .12 to .21 for mean arterial and systolic and diastolic pressure responses to the salt sensitivity maneuver, respectively. Corresponding heritability e stimates were 0.26 to 0.84, 0.26 to 0.74, and 0.004 to 0.24, respectiv ely. These data strongly suggest a heritable component of salt sensiti vity.