High-protein diet or unilateral nephrectomy induces a humoral factor(s) that enhances mesangial cell proliferation in culture.
BACKGROUND
A high-protein diet is one of the maneuvers which produce hypertrophy of kidney mass. The underlying mechanism(s) has not been elucidated. In the present study, we investigated the possibility that a humoral factor may be involved.


METHODS
Twenty-eight 3-week-old Charles River rats were studied. Fourteen underwent right nephrectomy and 14 sham operation. Each of these groups was divided into two equal subgroups (n = 7 in each): one maintained on a regular diet (20% protein) and the other on a high-protein diet (60% protein) for 7 days. Following this period the animals were sacrificed. Sera from the animals were added to mesangial cell cultures from kidneys of intact 3-week-old rats, and the thymidine incorporation was assessed.


RESULTS
The parameters of kidney mass indicated that the high-protein diet indeed produced kidney hypertrophy. Sera from the sham-nephrectomized animals fed a high-protein diet produced a significantly greater proliferative effect on mesangial cells in culture than sera from the respective animals on a normal-protein diet. Sera from either nephrectomized group or from the high-protein sham-operated group all had similar magnitudes of enhancement of mesangial cell proliferation.


CONCLUSIONS
We conclude that the renal hypertrophy produced by a high-protein diet is mediated, at least in part, by a humoral factor(s).
Weissgarten
J
J
Nephrology Division, Assaf Harofeh Medical Center, Zerifin, Israel.
Modai
D
D
Averbukh
M
M
Cohn
M
M
Berman
S
S
Averbukh
Z
Z
D000818:Animals; D001798:Blood Proteins / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004044:Dietary Proteins / Q000494:pharmacology*; D005920:Glomerular Mesangium / Q000166:cytology*; D006984:Hypertrophy; D007674:Kidney Diseases / Q000139:chemically induced / Q000473:pathology / Q000601:surgery; D009392:Nephrectomy; D009929:Organ Size; D051381:Rats; D011919:Rats, Inbred Strains
D001798:Blood Proteins; D004044:Dietary Proteins