Tissue Concentrations of Somatomedin C: Further Evidence for Multiple Sites of Synthesis and Paracrine or Autocrine Mechanisms of Action

We have validated a method for extracting and measuring the tissue content of somatomedin C (Sm-C)/insulin-like growth factor I (IGF-I), a growth-hormone-dependent, growth-promoting peptide. The Sm-C content of tissue extracts was strongly growth-hormone dependent because most of the tissues studied...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1984-02, Vol.81 (3), p.935-939
Main Authors: D'Ercole, A. Joseph, Stiles, Alan D., Underwood, Louis E.
Format: Article
Language:English
Subjects:
Animals
Blood
Growth Hormone - pharmacology
Hemoglobins
Hemoglobins - analysis
Human resources
Hypophysectomy
Insulin-Like Growth Factor I
Kidneys
Kinetics
Liver
Lungs
Male
Radioimmunoassay
Rats
Rats, Inbred Strains
Somatomedins
Somatomedins - biosynthesis
Somatomedins - isolation & purification
Somatomedins - physiology
Tissue Distribution
Tissue extracts
Vehicles
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Summary:We have validated a method for extracting and measuring the tissue content of somatomedin C (Sm-C)/insulin-like growth factor I (IGF-I), a growth-hormone-dependent, growth-promoting peptide. The Sm-C content of tissue extracts was strongly growth-hormone dependent because most of the tissues studied from hypophysectomized rats contained significantly less Sm-C than normal tissues. The intraperitoneal administration of ovine growth hormone (oGH) to hypophysectomized rats caused tissue extractable Sm-C to increase in kidney, liver, lung, heart, and testes. Tissue Sm-C responses to oGH were maximal after 12 hr, 6 hr before the maximal increment in serum. In liver and lung, the tissue Sm-C response to various doses of oGH fit linear regression models, and the doses of oGH needed to increase the Sm-C are in the range of those required to increase protein synthesis. Although these results do not exclude the possibility that the somatomedins act by hormone-like endocrine mechanisms, they add support to the concept that these peptides act through autocrine or paracrine mechanisms, being produced at multiple sites and acting at or near their sites of production.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.81.3.935