Simultaneous decreases of urinary sodium, potassium, and chloride excretions induced by Walking in children with mesangial cell proliferations

Abstract

The roles of proliferated glomerular mesangial cells in the regulation of glomerualar filtration rate and urinary sodium excretion are now in debate. Using 246 children aged 6 to 18 years with chance proteiuria and/or hematuria and biopsy-proved chronic glomrulonephritis (GN), we studied the relations between the severity of mesangial cell proliferations and the changes of fractional urinary sodium (Na), potassium (K), and chloride (Cl) excretions in response to standing and walking from sustained recumbencey. Greater decreases of urinary Na, K, and Cl excretions were found to be induced immediately after standing and walking in moderate to severe mesangial proliferative UN including membranoproliferative GN than in minimal change GN. Urinary Na/K rations were also decreased, but they were not relevant to the severity of mesangial cell proliferations, which suggested no significant role of aldosterone in the observed simultaneous decreases of urinary Na, K, and Cl excretions. These results suggest that the proliferated mesangial cells regulate and decrease simultaneously fractional urinary Na, K, and Cl excretions in response to positional changes from recumbence to standing and walking, presumably, by the contractile activity of mesangial cells and aldosterone seems to play no significant role in these processes. These non-invasive renal function tests may give an aid to estimate the presence and severity of glomerular mesangial cell proliferations in children with chance proteiuria and/or hematuria.