Beta 2-adrenoceptor density in fibroblast culture correlates with human NaCl sensitivity

Abstract

To study salt sensitivity in humans and its relation to expression of adrenoceptors, 20 male normotensive Caucasians were investigated on a diet of 180 mmol NaCl/day followed by 60 mmol NaCl/day over 2 wk and again by 180 mmol NaCl/day over 2 wk, and blood pressure changes were assessed by long-term oscillatory blood pressure monitoring under basal conditions. Individual cell cultures of skin fibroblasts from skin biopsies were also established, and alpha 2- and beta 2-adrenoceptors were measured. Seven subjects were salt sensitive, and the remainder were salt resistant. Cultured skin fibroblasts in salt-sensitive subjects express less than half the number of beta 2-adrenoceptors compared with salt-resistant subjects (65 +/- 12.7 vs. 173 +/- 14.8 fmol/mg, P less than 0.001), and there is a correlation between the absolute rise of blood pressure on a high-salt diet and the density of beta 2-adrenoceptors (r = -0.67, P less than 0.01). It remains to be established whether a reduced in vitro density of beta 2-adrenoceptors in cultured cells is causally related to salt sensitivity in normotensive humans.