Renal assimilation of oligopeptides: physiological mechanisms and
metabolic importance.
Adibi, Siamak A.
Clinical Nutrition Research Unit and Department of Medicine,
University of Pittsburgh School of Medicine, Pittsburgh, PA
APStracts 4:0018E, 1997.
Assimilation of systemic oligopeptides (di-and tripeptides), is
largely a function of kidneys. The most specific and unique mechanism
utilized for the performance of this renal function, is transport
followed by intracellular hydrolysis and then release of constituent
amino acids to the systemic circulation. Among tissues examined
(liver, kidney, intestine, and muscle), kidney is the only tissue
capable of accumulating dipeptides in concentrations which are
greater than their plasma concentrations and also is the tissue with
the highest cytoplasmic dipeptidase activity. Intracellular
accumulation is mediated by two transporters (Pept-1 and Pept-2) both
of which have been recently cloned. These transporters use dipeptides
and tripeptides as substrates and rely on protons and membrane
potential for their driving force. Pept-1 is a low affinity/high
capacity and Pept-2 is a high affinity/low capacity transporter. The
nutritional and metabolic regulation of renal assimilation of
oligopeptides is suggested by the selective decrease in dipeptide
balance across the kidneys of starved human subjects and by the
insulin stimulation of dipeptide transport by a renal cell line.
Peptiduria has been observed in a variety of diseases but the
mechanism, except in genetic diseases affecting hydrolysis of
oligopeptides, is not known. Finally, the capacity for active
transport of oligopeptides and peptidomimetic drugs enables kidneys
to play major roles in nutritional and pharmacological therapies.
Received 24 June 1996; accepted in final form 13 January 1997.
APS Manuscript Number E300-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 19 February 1997