AJP - Regulatory, Integrative and Comparative Physiology, Vol 248, Issue 6 739-R747, Copyright © 1985 by American Physiological Society
Fluctuations in basal plasma levels of pancreatic polypeptide in monkeys and humans
B. C. Hansen, K. L. Jen, S. B. Pek and R. A. Wolfe
We reported that significant rapid oscillations occur in basal plasma
levels of insulin, glucagon, and glucose in rhesus monkeys and humans. We
searched for evidence for similar spontaneous fluctuations also in plasma
levels of pancreatic polypeptide (PP). Mean +/- SE basal plasma levels of
PP were 236 +/- 15 pg/ml in 11 monkeys, 64 +/- 12 in nine normal-weight
human subjects, and 74 +/- 10 in nine obese human subjects. 1) PP levels
fluctuated with periods of 6-26 min. The fluctuations in PP were less
regular than and did not temporally correlate with the fluctuations in
plasma levels of insulin, glucagon, or glucose (usual periods 8-12 min). 2)
In human subjects the concentration but not the periodicity of PP was
related to obesity. 3) Comparisons of simultaneously determined levels of
PP in portal and central venous plasma of monkeys suggested that PP may be
extracted to varying degrees by the liver, even under basal well-controlled
conditions, and that neither the size of the PP portal-central gradient nor
the period and amplitude of fluctuations was associated with PP
concentration. We conclude that plasma PP levels fluctuate with such a
large amplitude that these fluctuations must be considered in the
interpretation of experimental results based on limited numbers of samples.
