Objective: To study the effects of genetics on the response of platelet alpha 2-adrenoceptors to a change in salt intake.
Methods: Biochemical measurements and radioligand binding assays in platelets were performed in 11 normotensive male university students with a family history of essential hypertension (FH+) and in 17 students without a family history of hypertension (FH-). The 28 students were fed a high-sodium diet for 7 days and a low-sodium diet for 7 days.
Results: In FH+ subjects the number of alpha 2-adrenergic receptors on platelet membrane fractions increased significantly from the high-sodium diet to the low-sodium diet, even though plasma noradrenaline concentrations tended to increase with the low-sodium diet. There was no change in the number of alpha 2-adrenoceptors in the FH--group. In both groups the radioligand binding affinity was decreased during a low-sodium period compared with in a high-sodium period.
Conclusion: In the FH+ subjects the change in platelet alpha 2-adrenoceptors associated with altered sodium status was similar to that seen in patients with salt-sensitive hypertension, suggesting that there is a genetic susceptibility to sodium.