AJP - Endocrinology and Metabolism, Vol 240, Issue 2 79-E82, Copyright © 1981 by American Physiological Society
Human and rat growth hormones enhance guanylate cyclase activity
D. L. Vesely
The objective of this investigation was to determine whether physiological
levels of growth hormone have part of their mechanism of action through
stimulation of guanylate cyclase (EC 4.6.1.2.). Rat and human growth
hormones enhanced the activity of soluble guanylate cyclase two- to
fourfold in rat gracilis anticus skeletal muscle, liver, lung, heart,
pancreas, and kidney cortex at a concentration of 10 nM. Dose-response
relationships revealed that more than half-maximal stimulation of guanylate
cyclase activity was seen at a concentration as low as 10 nM and
nonstimulation of guanylate cyclase activity was seen when the
concentration was decreased to 1 nM. Maximal enhancement was seen at 100 nM
of growth hormone, and there was no further enhancement when the
concentration was increased to the micromolar or millimolar range. Thus,
the data in this investigation indicate that at concentrations at which
growth hormone is known to cause its growth-promoting effects, growth
hormone does cause an enhancement of the activity of the guanylate
cyclase-cyclic GMP system.
