HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 102/1/214    most recent 01205.2005v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Olesen, J. L. Articles by Langberg, H. Search for Related Content PubMed PubMed Citation Articles by Olesen, J. L. Articles by Langberg, H.

Exercise-dependent IGF-I, IGFBPs, and type I collagen changes in human peritendinous connective tissue determined by microdialysis

¹Institute of Sports Medicine, Bispebjerg Hospital, Copenhagen; and ²Medical Research Laboratories, Aarhus University Hospital, Aarhus, Denmark

Submitted 22 September 2005 ; accepted in final form 21 August 2006

Microdialysis studies indicate that mechanical loading of human tendon during exercise elevates type I collagen production in tendon. However, the possibility that the insertion of microdialysis fibers per se may increase the local collagen production due to trauma has not been explored. Insulin-like growth factor I (IGF-I) and its binding proteins (IGFBPs), which are known to stimulate collagen production in animal tendons, may regulate the translation of mechanical loading to collagen synthesis. Systemic and tissue levels of IGF-I, IGFBP, and type I collagen metabolism markers [procollagen I COOH-terminal propeptide (PICP) and COOH-terminal telopeptide of type I collagen] were measured by microdialysis in peritendinous tissue of the human Achilles tendon in an exercise group (performing a 36-km run, n = 6) and a control group (no intervention, n = 6). An increase in local PICP concentration was seen in both groups after 72 h and stayed elevated in the exercise group at 96 h (P < 0.05). IGFBP-1 in both serum and dialysate increased in the exercise group immediately after exercise (P < 0.05), whereas IGFBP-3 decreased systemically (P < 0.05). Elevation of local IGFBP-4 was observed in both the control and exercise groups after 48 h (P < 0.05). Total IGF-I did not change in locally or systemically in either group. Our results indicate an increased local production of PICP in human peritendinous tissue in response to prolonged mechanical loading with part of the increase due to trauma from the sampling technique. Care must therefore be emphasized to minimize the numbers of insertions with microdialysis. We demonstrated an elevation of IGFBP-1 both systemically and peritendinously in response to prolonged acute exercise. The local increased collagen synthesis was preceded by an elevation of local concentration of IGFBP-4, suggesting that IGFBP-4 may have a key role in the IGF-axis effect on the human collagen synthesis in vivo.

tendon; insulin-like growth factor I; insulin-like growth factor binding proteins; microdialysis; mechanical loading; human

This article has been cited by other articles:

				U Berg, T Gustafsson, C J Sundberg, L Kaijser, C Carlsson-Skwirut, and P Bang Interstitial IGF-I in exercising skeletal muscle in women Eur. J. Endocrinol., October 1, 2007; 157(4): 427 - 435. [Abstract] [Full Text] [PDF]