Minimally invasive sampling of transdermal body fluid for the purpose of measuring insulin-like growth factor-I during exercise training. Diabetes Technol Ther 2006 Apr;8(2):244-52 PMID: 16734553
Insulin-like growth factor-I (IGF-I) is a ubiquitous hormone that is secreted in both an endocrine and an autocrine/paracrine manner. IGF-I has conventionally been measured in serum; however, transdermal body fluid (TDF) remains as an unexplored biocompartment in which IGF-I also resides and may be more biologically relevant because of its proximity to tissues and cells. The purpose of this study was to compare IGF-I in serum versus IGF-I in TDF before and after 8 weeks of physical training. Twenty-eight healthy men (28 +/- 5 years old, 176 +/- 8 cm tall, weighing 83 +/- 11 kg) had TDF obtained by a novel, minimally invasive method that included the application of continuous vacuum pressure on forearm skin perforated with tiny micropores created by a focused beam from a laser system and also had blood obtained by venipuncture. An enzyme-linked immunosorbent assay measured total IGF-I concentrations. A repeated-measures analysis of variance (biocompartment x time) and Pearson Product Moment Correlation coefficients (P < or = 0.05) were used for statistical analyses. Data are presented as mean +/- SE. Total TDF IGF-I was significantly lower than serum IGF-I both before (TDF, 91 +/- 6 ng/mL; serum, 375 +/- 17 ng/mL) and after (TDF, 83 +/- 5 ng/mL; serum, 363 +/- 19 ng/mL) the exercise training. Serum and TDF IGF-I values were not significantly different pre- to post-training. Serum and TDF IGF-I levels were significantly correlated pre-training (r = 0.41), but not post-training (r = 0.34). The percent change between serum and TDF was not correlated (r = 0.09). This study has demonstrated that total IGF-I can be sampled and measured in TDF via a minimally invasive manner and is appreciably (approximately 76%) less than total IGF-I measured in serum. Additionally, the IGF-I measurements in these two biocompartments were not closely associated, possibly indicating an uncoupled, rather than a linked, regulation of IGF-I among the body's biocompartments.
Author ListNindl BC, Tuckow AP, Alemany JA, Harman EA, Rarick KR, Staab JS, Faupel ML, Khosravi MJ
AuthorKevin Richard Rarick PhD Assistant Professor in the Pediatrics department at Medical College of Wisconsin
MESH terms used to index this publicationLasers
Insulin-Like Growth Factor I
Physical Education and Training
View this publication's entry at the Pubmed website PMID: 16734553