Role of the kidney in human leptin metabolism.
Meyer, Christian, Dave Robson, Noya Rackovsky, Veena Nadkarni, and
John Gerich.
University of Rochester School of Medicine, Departments of Medicine
and Physiology and Pharmacology, Rochester, New York
APStracts 4:0166E, 1997.
To assess the role of the human kidney in leptin metabolism, we
measured renal leptin net balance and urinary leptin excretion in 16
normal postabsorptive volunteers with varying degrees of obesity.
Arterial leptin concentrations (11.6 +/- 2.7 ng/ml) significantly
exceeded renal vein concentrations (10.3 +/- 2.5 ng/ml, p < 0.001).
Renal leptin fractional extraction averaged 13.1 +/- 1.1 % and renal
leptin net balance (uptake) averaged 1070 +/- 253 ng/min. Lineweaver
Burk analysis indicated renal leptin uptake followed saturation
kinetics with an apparent K[mu] of 10.9 ng/ml and Vmax of 1730
ng/min, respectively. Leptin was generally undetectable in urine.
Using literature values for systemic leptin clearance, it was
calculated that renal leptin uptake could account for approximately
80 % of all leptin removal from plasma. These data indicate that the
human kidney plays a substantial role in leptin removal from plasma
by taking up and degrading the peptide.
Received 21 April 1997; accepted in final form 23 July 1997.
APS Manuscript Number E182-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 27 August 1997