DIFFERENTIAL SODIUM-REGULATION BETWEEN SALT-SENSITIVE AND SALT-RESISTANT SABRA RATS IS NOT DUE TO ANY MUTATION IN THE RENAL ALPHA-B-2-ADRENOCEPTOR GENE

A defect in sodium modulation of density and agonist affinity of renal alpha(2)-adrenoceptor exists in normotensive salt-resistant Sabra (SB N) rats when compared to hypertensive salt-sensitive (SBH). A highly c onserved aspartic acid residue in the second helix has been implicated in sodium regulation of alpha(2)-adrenoceptor-ligand interactions. As the alpha(2)B-adrenoceptor subtype is preponderantly present in kidne y of SBH and SBN rats, a mutation might distinguish this subtype betwe en SBH and SBN rats. From this study, no difference between SBH and SB N alpha(2)B-adrenoceptor gene could be demonstrated in terms of nucleo tide sequence. These data suggest that in Sabra rats, the differential sodium regulation in density and agonist affinity between renal SBH a nd SBN alpha(2)-adrenoceptor may have another origin than the alpha(2) B-adrenoceptor encoding gene.