AJP - Endocrinology and Metabolism, Vol 252, Issue 4 E549-E556, Copyright © 1987 by American Physiological Society
Impact of intensive venous sampling on characterization of pulsatile GH release
W. S. Evans, A. C. Faria, E. Christiansen, K. Y. Ho, J. Weiss, A. D. Rogol, M. L. Johnson, R. M. Blizzard, J. D. Veldhuis and M. O. Thorner
The effect of sampling intensity on quantitative properties of pulsatile
growth hormone (GH) release was tested using an objective, statistically
based pulse detection algorithm (Cluster). Seven normal young men had blood
withdrawn at 5-min intervals for 24 h. The number of GH peaks/24 h (mean
+/- SE) detected in the 5-min series (5.93 +/- 0.66) was significantly
greater than the number of peaks documented in the constituent 10-min (3.45
+/- 0.28), 15-min (2.79 +/- 0.31), 20-min (2.86 +/- 0.64), 30-min (2.5 +/-
0.36), 45-min (2.21 +/- 0.21), and 60-min (1.93 +/- 0.23) series. The
increased number of peaks detected with 5-min sampling reflected
high-frequency pulsatile GH release occurring within the major GH secretory
episodes. Both the mean widths and areas associated with peaks identified
in the 5-min series were smaller than those documented with less intensive
sampling. Peak amplitude did not change with sampling intensity. These data
suggest that the major secretory episodes of GH release in normal young men
encompass high-frequency GH secretory activity. That these high-frequency
GH secretory events have not previously been described probably reflects
the relatively infrequent sampling paradigms (e.g., every 20-30 min)
commonly used in the past.
