Genetic Influences on the Response to Dietary Salt Reduction, Acute Salt Loading, or Salt Depletion in Humans

The effect of heredity on blood pressure is established. However, not all genetically predisposed individuals develop an elevated blood pressure. Thus, an environmental factor may also be required for expression of this genetic predisposition. To elucidate this effect further, as well as to examine the relationship between inherited factors and the influence of salt intake, we conducted acute and chronic investigations in normal subjects. We present evidence that renal function, the renin-angiotensin-aldosterone system, and sympathetic nervous system are all influenced by genetic variance. We found that the blood pressure response to both acute changes in volume and changes in salt intake is normally distributed, supporting the notion of salt sensitivity and resistance of blood pressure. We identified phenotypes of haptoglobin as possibly useful indicators of salt sensitivity and resistance. We documented a parent-offspring resemblance in blood pressure and also a maternal-offspring resemblance in the change in blood pressure with salt reduction. We present evidence that suggests that salt-sensitive persons exhibit differences in renin-aldosterone relationships and natriuretic responses consistent with volume expansion compared to salt-resistant individuals. Finally, we identified a potential role for altered adrenoreceptors in the development of salt sensitivity. Our observations speak to the inherited nature of salt sensitivity and resistance of blood pressure. They may have mechanistic implications as well.