We have previously reported that in vivo insulin action, measured both during oral glucose tolerance testing and post-prandial muscle glycogen accumulation, is impaired in an animal model of essential hypertension, the SHR. In vivo insulin action reflects both tissue responsiveness as well as substrate and hormone availability at the tissue level. In order to evaluate tissue responsiveness in vitro, we examined two parameters of insulin action: 1) muscle glycogen synthesis using 3H-glucose; and, 2) muscle glucose transport using 3H-2-deoxy-glucose (3H-2-DG). Extensor digitorum longus (EDL) strips were obtained from 13-week old SHR and WKY and were incubated in the absence or presence of pharmacological insulin and radiolabelled glucose analogues. Results (mean ± SD): IN VITRO GLYCOGEN SYNTHESIS (dpm 3H-glucose/mg EDL) IN VITRO GLUCOSE TRANSPORT (dpm 3H-2-DG/mg EDL) Insulin (μU/ML) WKY SHR Insulin (μU/mL) WKY SHR 0 377±120 289±89 0 483±74 516±61 1000 439±175 565±187 500 785±369 997±347 P <05 <05 P <.03 <.001 We conclude that both muscle glucose transport and glycogen synthesis were stimulated to a comparable degree by insulin in EDL strips from WKY and SHR; there were no significant differences between WKY and SHR. This suggests that the observed impairment in in vivo insulin action results not from differences in tissue responsiveness to insulin, but from differences in hormone or substrate availability at the tissue level.
|Original language||English (US)|
|Journal||Journal of Investigative Medicine|
|State||Published - 1996|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)