Growth hormone response induced by synthetic human growth hormone-releasing factor (1-44) in healthy dogs.

The growth hormone (GH) secretory response to varying doses (1, 5 and 25 micrograms/kg) of intravenous (i.v.) human GH releasing factor (GRF) (1-44) was measured in four, 16-month-old female dogs and compared to the GH response to placebo (vehicle solubilizing GRF) and standard clonidine test (10 micrograms/kg i.v.). The three doses of GRF had no apparent clinical side effects and were capable of eliciting a rapid increase in the mean plasma GH level. The rise in plasma GH occurred within 5 minutes with a peak response at 15-30 minutes. However inter-subject variability of the GH response was large in terms of magnitude and time course. By analysis of the areas under the response curves it was shown that GRF 1-44 was as effective in stimulating GH release as clonidine and that a dose of 1 microgram/kg GRF 1-44 could be a good choice for use as a standard test dose in the dog.