A NOVEL VARIANT OF THE BETA-SUBUNIT OF THE AMILORIDE-SENSITIVE SODIUM-CHANNEL IN AFRICAN-AMERICANS

The amiloride-sensitive sodium channel is responsible for the rate-lim iting step of sodium reabsorption in the distal renal tubule, and thus may play a key role in the maintenance of sodium balance and blood pr essure, In this study, a genetic variant that results in a change of t hreonine to methionine at amino acid 594 (T594 M) in the carboxy-termi nus of the beta-subunit of the amiloride-sensitive sodium channel has been identified. This variant was present in 6.1% of African-American subjects (N = 231) but was not seen in Caucasians (N = 192), Whole cel l voltage clamp of B-lymphocytes from individuals with the T594 M vari ant showed similar basal membrane slope conductance, compared with the wild-type but increased response to cAMP analog.