G-protein beta3 subunit 825T allele and response to dietary salt in normotensive men
Schorr, U.; Blaschke, K.; Beige, J.; Distler, A.; Sharma, A.M.
Journal of Hypertension 18(7): 855-859
2000
ISSN/ISBN: 0263-6352 PMID: 10930182 Document Number: 515361
Background and aims: A functional single-nucleotide variant of the gene encoding the beta3 subunit of heterotrimeric G proteins (Gbeta3 C825T), associated with enhanced G-protein activation and increased activity of the sodium-proton exchanger (NHE1), has been implicated in the development of hypertension. Given the possible involvement of NHE1 in sodium homeostasis, we tested the hypothesis that the Gbeta3 825T allele determines the response of the renin-angiotensin system and blood pressure to dietary salt restriction. Methods: Young normotensive men (20-30 years old, n = 193) were recruited within the framework of the Berlin Salt-Sensitivity Trial and studied on low- (20 mmol/day) and high-salt (220 mmol/day) dietary protocols. Subjects were characterized for parameters of the renin-angiotensin system and blood pressure response and genotyped for the Gbeta3 C825T polymorphism. Results: The genotype distribution was in Hardy-Weinberg equilibrium (CC = 90, CT = 81 and TT = 22). The responses of the renin-angiotensin system and blood pressure to the dietary protocol were virtually identical between the genotypic groups. Furthermore, when subjects were classified as salt-resistant (n = 145) or salt-sensitive (n = 48), genotype distribution was comparable between the two groups (salt-resistant: TT = 17, CT = 60, CC = 68, qT = 0.32; salt-sensitive: TT = 5, CT = 21, CC = 22, qT = 0.32). Conclusion: These findings do not support the hypothesis that the Gbeta3 C825T polymorphism determines the response of the renin-angiotensin system to salt depletion or can serve as an early genetic marker of salt sensitivity in young normotensive men.