Plasma GH and somatomedin C responses to single and repeated administrations of human growth hormone releasing factor (hGRF).
Plasma growth hormone (GH) and somatomedin C responses to single and repeated administrations of synthetic human growth hormone releasing factor (hGRF-44) were studied in 29 patients with GH deficiency. hGRF-44 administered by single iv bolus (10 micrograms/kg), repeated iv boluses (50 or 100 micrograms, once a day), repeated iv infusions (2.5 micrograms/min for 90 min, once a day), and/or repeated im injections (100 micrograms, twice a day) for three to six consecutive days. Ten of 16 patients had plasma GH responses to a single iv bolus injection, i.e., their plasma GH increased above 5 ng/ml or twice the basal level. However none of them showed a plasma somatomedin C increase. To repeated iv bolus injections and repeated iv infusions of hGRF-44, 7 of 17 patients showed plasma GH responses, however in none of 7 patients did somatomedin C increase. Plasma somatomedin C did not increase after repeated im administrations of hGRF-44 for 5 days. Plasma somatomedin C increase was observed in two patients, from 0.32 to 0.54 U/ml and from 0.16 to 0.46 U/ml, in response to repeated iv boluses and repeated iv infusions, respectively. These results suggest that hGRF-44 stimulates plasma GH secretion in some patients with GH deficiency, however the increases are not enough to stimulate somatomedin generation.
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D005260:Female; D006130:Growth Disorders / Q000188:drug therapy*; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007334:Insulin-Like Growth Factor I; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology* / Q000627:therapeutic use; D012636:Secretory Rate / Q000187:drug effects; D013002:Somatomedins / Q000378:metabolism*
D010446:Peptide Fragments; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone