A pulsatile mode of insulin secretion accounts for approximately
seventy percent of total insulin secreted during fasting: direct in
vivo measurements by two newly validated independent methods.
Porksen, Niels, Stephen Munn, Jeffery Steers, Stephen Vore, Johannes
Veldhuis, Peter Butler.
Endocrine Research Unit, and Division of Transplant Surgery, Mayo
Clinic, Rochester, MN, 55905; Department of Medicine and NSF Center
for Biological Timing, Charlottesville, VA, 22908; Department of
Comparative Medicine, East Carolina School of Medicine, Greenville,
NC, 27858
APStracts 2:0096E, 1995.
The purpose of the present study was to determine the contributions of
discrete insulin secretory bursts versus basal insulin release to
total insulin secretion in vivo. Quantification of the partitioning
of pulsatile and basal insulin secretion is complicated by
physiological delivery of these pulses into the portal vein and the
absence of validated methods of measuring the rates of pulsatile and
basal insulin secretion in vivo. We therefore (a) developed a canine
model with chronically implanted portal vein catheters, (b) validated
an established deconvolution technique as well as a novel direct
catheterization technique (Clustcath) for measurement of pulsatile
and non-pulsatile insulin secretion rates in this model, and (c)
applied these methods to study insulin secretion in the overnight
-fasted dog in vivo to determine the contribution of pulsatile versus
basal insulin secretion to total rates of endogenous insulin
secretion. Rates of total, pulsatile, and non-pulsatile endogenous
insulin secretion measured by Clustcath closely parallel those
measured by deconvolution analysis (54+/-15 vs 51+/-11, 38+/-12 vs
36+/-11 and 16+/-4 vs 14+/-4 pmol/min). Both Clustcath and
deconvolution indicated that the majority of insulin was secreted as
pulses (70+/-6 and 66+/-7%, respectively). These data infer that any
process that selectively decreases the pulsatile component of insulin
secretion (e.g., diabetes mellitus) will likely have a major impact
on total insulin secretion.
Received 14 February 1995; accepted in final form 27 March 1995.
APS Manuscript Number E63-5.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 9 May 1995.