Cardiosteroids and Genetic Factors in the Development of Salt-Sensitive Hypertension in Georgian Subjects

The goal of study was to elucidate the role of genetic factors and cardiosteroids (endogenous ouabain (EO) and marinobufagenin (MBG) in the development of salt-sensitivity and salt-sensitive hypertension in Georgian patients.
Objectives: Typing of normotensive and hypertensive subjects by salt-sensitivity test, identification of salt-sensitivity associated genes polymorphismss (ABCB1, CyP3A5, Cyp11B2) and detection of circulating levels of cardiosteroids in salt-sensitive normotensive and hypertensive subjects during low and high salt diet.
Methods: A total of 72 ethnically Georgian middle-aged (42 females and 30 males) subjects (22 normotensives and 50 hypertensives) of stage I essential hypertension (JNC VIII) were examined. All subjects were tested for salt-sensitivity. Genetic testing for ABCB1, CyP3A5 and CyP11B2 polymorphisms was preceded by DNA extraction with QUAGEN DNA Blood Mini Kit. Plasma and urine levels of MBG and EO were measured using ELISA and RIA methods.
Results of our study showed that Georgian both healthy and hypertensive subjects consume high amount of sodium. Salt-sensitivity was detected in 12 (54,5%) of normotensive subjects and in 32 (64%) of hypertensive patients. In salt-sensitive hypertensives plasma leels of both MBG and EO significantly exceeded those of salt-resistant patients. Genetic studies showed that the highest incidence was detected with CYP3A5 3*/3* polymorphism (90,4%). The latter positively correlated with salt-sensitivity (r=0,58, p<0,05).
Conclusion: We would suggest that high incidence of salt-sensitivity related genotypes in Georgian population might serve as a markers for identification of risk groups for the development of salt-sensitive hypertension and provide useful tool for its primary prevention and rational treatment.