Am. Sharma et al., DIETARY NU-INTRAVENOUS SALT LOADING FOR THE ASSESSMENT OF SALT SENSITIVITY IN NORMOTENSIVE MEN, American journal of hypertension, 7(12), 1994, pp. 1070-1075
The purpose of this study was to compare the blood pressure response t
o two commonly used protocols for the assessment of salt sensitivity i
n normotensive men, involving either the rapid intravenous administrat
ion of a saline load followed by diuretic-induced salt depletion, or t
he more physiologic but time-consuming approach involving dietary salt
depletion and repletion. Twenty-two healthy male volunteers (22-35 ye
ars old) were given a saline load (2 L of 0.9% NaCl over 4 h, iv), and
on the following day, a low-salt diet (20 mmol NaCl) and furosemide (
3 x 40 mg, po). Resting mean arterial blood pressure (MABP) was assess
ed after the saline load and on the morning following salt depletion,
After a 2-week wash-out period, subjects were given a low-salt diet (2
0 mmol/day NaCl) for 2 weeks, supplemented by either 220 mmol/day NaCl
or placebo for 1 week each. At the end of each week, resting MABP was
assessed in the supine subjects. Although MABP changes were quite var
iable (iv, mean -2.1 mm Hg; range, -9.1 to +5.6; diet, mean -2.0 mm Hg
; range, -14.3 to +7.2), there was a significant correlation between t
he salt-induced changes in MABP (r = 0.56, P <.01) and diastolic blood
pressure (r = 0.56, P <.01) between the two protocols. However, in in
dividual subjects, blood pressure response to the intravenous protocol
did not uniformly predict the blood pressure response to the dietary
protocol. Thus, despite a modest correlation between the changes in bl
ood pressure induced by the two protocols, the value of the infusion p
rotocol for the identification of individuals who respond with a chang
e in blood pressure to dietary salt restriction appears limited.