G-protein beta3-subunit gene variant, blood pressure and erythrocyte sodium/lithium countertransport in essential hypertension.
Recently, a C825T polymorphism in the gene coding for the beta3 subunit of G proteins (GNB3) has been described in cells from patients with essential hypertension and enhanced Na+/H+ exchange activity. This study aims to evaluate the association between the 825T allele and activity of erythrocyte sodium/lithium countertransport (Na+/Li+ CT) and other sodium transport systems in red blood cells from patients with essential hypertension. A group of 77 patients (36 male, 41 female; aged 51.7 +/- 1.1 years) was studied. The maximal rates (Vmax) of Na+/Li+ CT, Na+/K+/Cl- cotransport and Na+K+ ATPase were evaluated in erythrocytes from all the patients. They were genotyped for the C825T polymorphism by a polymerase chain reaction (PCR) method, followed by digestion with BseDI. Body mass index (BMI) was higher in CT+TT patients than in CC patients (28.9 +/- 0.5 vs. 27.0 +/- 0.7 kg/m2; P=0.023). Hypertensives with the T allele (CT+TT genotypes) showed significantly higher systolic blood pressure (BP) values (156.9 +/- 2.1 vs. 148.9 +/- 2.8 mmHg; P=0.024), whereas differences in diastolic BP did not reach statistical significance (96.4 +/- 1.0 vs. 94.0 +/- 1.1 mmHg; P=0.120). No differences in the Vmax of Na+/Li+ CT between the genotypes was seen (CC: 236 +/- 19 and CT+TT 277 +/- 23 mmol/L cells per h; P=0.221). Similarly, no differences were detected in the Vmax of erythrocyte Na+/K+/Cl- cotransport and Na+K+ ATPase among the genotypes. There was no appreciable association between the G-protein beta3-subunit C825T polymorphism and erythrocyte Na+/Li+ CT and other sodium transport systems in the hypertensive patient sample studied; however, those with the T allele were more obese and had more severe systolic hypertension.
Servicio de Nefrología, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Hospital Clínic, Universidad de Barcelona, Spain. epoch@medicina.ub.es
Esteban
E
Poch
Daniel
D
González-Núñez
Montserrat
M
Compte
Alejandro
A
De la Sierra
D017920:Antiporters / Q000097:blood*; D001794:Blood Pressure; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics*; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic
D017920:Antiporters; C454420:G-protein beta3 subunit; C045885:sodium-lithium countertransporter; D020962:Heterotrimeric GTP-Binding Proteins