Behavioural stress blunts the creatinine clearance increase induced by a protein load in healthy subjects

Background: The aim of this study was to investigate how behavioural states related to different levels of stress affected the increments of glomerula r filtration rate induced by an acute protein load. Methods: Thirteen healthy subjects were enrolled. Each subject was studied from 9:00 h to 15:00 h on two consecutive days. In random order, after a pr otein meal (1.2 g/kg b.w. of protein), each subject was required to remain in a relaxing, sitting position (resting period, R), or to solve graphical and mathematical problems (behavioural stress period, S). Mean blood pressu re (MBP) and heart rate (HR) were monitored by an ambulatory blood pressure device. Urine samples collected in each period were used to measure glomer ular filtration rate (GFR, creatinine clearance) and urinary sodium excreti on (UNa+V). Results: Significant decreases in MBP and HR were observed during the resti ng period after the protein load, which significantly increased GER. There was also a large increase of UNa+V. During S, the GFR changes were no longe r seen whereas the increse of UNa+V was maintained HR and MBP did not chang e compared to the prestimulus period. Conclusions: We conclude that in healthy subjects behavioural stress can bl unt the increase in GFR that follows a protein load, presumably by neuro-hu moral activated mechanisms. In our experimental conditions, behavioural str ess did not affect UNa+V.