Diabetes Care, Vol 16, Issue 8 1071-1075, Copyright © 1993 by American Diabetes Association
Renal effects of different types of protein in healthy volunteer subjects and diabetic patients
H Nakamura, S Ito, N Ebe and A Shibata
First Department of Internal Medicine, Niigata University School of Medicine, Japan.
OBJECTIVE--To evaluate the effects of acute loading of protein from
different sources on the glomerular filtration rate. RESEARCH DESIGN AND
METHODS--A total of 6 healthy volunteer subjects and 6 diabetic patients
with normoalbuminuria were studied before and after ingestion on separate
days of tuna fish containing 0.7 g/kg body wt of protein, boiled egg white
containing the same amount of protein as the tuna fish, or boiled egg white
containing 1.4 g/kg body wt of protein. Furthermore, to study the possible
role of prostaglandins and amino acids in the response of GFR to protein
loading, urinary excretion of prostaglandins, and plasma levels of amino
acids were measured during these tests. RESULTS--In normal subjects, the
GFR rose significantly (P < 0.01) after ingestion of tuna fish. No
significant differences were found between GFR before and after ingestion
of the different amounts of egg white. The GFRs of the diabetic patients
after ingestion of each of the meals were similar to the responses in
healthy volunteers. Plasma levels of Gly and Ala (amino acids known to
induce glomerular hyperfiltration) were higher after ingestion of tuna fish
than after administration of egg white in all subjects. No differences were
found in the plasma concentrations of any amino acids except Gly and Ala
after loads of tuna fish and egg white containing 1.4 g/kg of protein.
Urinary 6-keto-PGF1a excretion increased significantly (P < 0.01) after
tuna fish loading, but did not change after egg white challenge.
CONCLUSIONS--These findings could be explained either by differences in
renal vasodilatory prostaglandin secretion or by increased plasma levels of
Gly and Ala, which were increased only after ingestion of tuna fish. Thus,
egg white has renal effects on GFR different from those of tuna fish,
independent of the quantity of protein ingested.