Diabetes Care, Vol 17, Issue 7 711-715, Copyright © 1994 by American Diabetes Association
Mechanism of glomerular hyperfiltration after a protein meal in humans. Role of hormones and amino acids
KS Nair, RC Pabico, JA Truglia, BA McKenna, M Statt and DH Lockwood
Department of Medicine, University of Rochester School of Medicine and Dentistry, New York.
OBJECTIVES--Previous studies demonstrated that protein meals and amino acid
(AA) infusions increase glomerular filtration rate (GFR) and renal plasma
flow (RPF) and that somatostatin (SRIH) infusion inhibits these increments.
We tested whether a single AA such as alanine could increase GFR and RPF
and whether the changes in GFR and RPF could be explained on the basis of
changes in glucagon, growth hormone (GH), and insulin. RESEARCH DESIGN AND
METHODS--In the first experiment, alanine was infused with or without SRIH
in five normal subjects. In the second experiment, five other subjects were
infused with SRIH on three separate occasions. In a control study, insulin,
glucagon, and GH were given at replacement doses; in a hyperglucagonemia
study, glucagon was given at a rate of 0.2 microgram.kg-1.h-1
(hypoglucagonemia); and in a high GH study, GH was given at a rate of 2
micrograms.kg-1.h-1. GFR and RPF were measured using insulin and
para-aminohippurate, respectively. RESULTS--Alanine increased GFR and RPF,
whereas SRIH inhibited these changes (P < 0.05). Hyperglucagonemia or
high GH with or without insulin failed to increase RPF or GFR.
CONCLUSIONS--A single AA such as alanine increases GFR and RPF, and this
increase is dependent on a factor inhibited by SRIH. Although GH, glucagon,
and insulin are factors inhibited by SRIH, none of these factors explains
the changes in RPF and GFR in our acute studies.