Effect of insulin-like factors on glucose transport activity in unweighted rat skeletal muscle

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Abstract

We have previously demonstrated that mechanical unweighting of the soleus muscle by hindlimb suspension leads to increases in insulin receptor binding, muscle/fat-specific glucose transporter (GLUT-4) protein levels, and insulin- stimulated glucose transport activity. The present study used a novel approach to further evaluate the potential role of postreceptor binding mechanisms in this enhanced insulin effect after unweighting. Insulin-like growth factor I (IGF-I), vanadate, and phospholipase C were used to stimulate glucose transport activity independently of insulin receptor binding. Soleus glucose transport activity (assessed by 2-deoxyglucose uptake) was evaluated in vitro with soleus strips (~18 mg). Progressively increased responses to maximally effective doses of insulin or IGF-I were observed after 3 and 6 days of unweighting compared with weight-matched control strips. Enhanced maximal responses to vanadate (6 days only) and phospholipase C (3 and 6 days) for 2-deoxyglucose uptake were also observed. The results of this study 1) provide evidence that post-insulin receptor binding mechanisms also play a role in the enhanced response of the insulin-dependent pathway for stimulation of glucose transport in unweighted skeletal muscle and 2) indicate that IGF-I action on glucose transport is included in this enhanced response in unweighted muscle.

Original languageEnglish (US)
Pages (from-to)820-824
Number of pages5
JournalJournal of Applied Physiology
Volume75
Issue number2
StatePublished - 1993

Fingerprint

Skeletal Muscle
Insulin
Insulin Receptor
Glucose
Insulin-Like Growth Factor I
Vanadates
Deoxyglucose
Type C Phospholipases
Glucose Transporter Type 4
Hindlimb Suspension
Muscles
Facilitative Glucose Transport Proteins
Fats
Weights and Measures

Keywords

  • 2-deoxyglucose uptake
  • insulin
  • insulin- like growth factor I
  • phospholipase C
  • simulated weightlessness
  • soleus
  • vanadate

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

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title = "Effect of insulin-like factors on glucose transport activity in unweighted rat skeletal muscle",
abstract = "We have previously demonstrated that mechanical unweighting of the soleus muscle by hindlimb suspension leads to increases in insulin receptor binding, muscle/fat-specific glucose transporter (GLUT-4) protein levels, and insulin- stimulated glucose transport activity. The present study used a novel approach to further evaluate the potential role of postreceptor binding mechanisms in this enhanced insulin effect after unweighting. Insulin-like growth factor I (IGF-I), vanadate, and phospholipase C were used to stimulate glucose transport activity independently of insulin receptor binding. Soleus glucose transport activity (assessed by 2-deoxyglucose uptake) was evaluated in vitro with soleus strips (~18 mg). Progressively increased responses to maximally effective doses of insulin or IGF-I were observed after 3 and 6 days of unweighting compared with weight-matched control strips. Enhanced maximal responses to vanadate (6 days only) and phospholipase C (3 and 6 days) for 2-deoxyglucose uptake were also observed. The results of this study 1) provide evidence that post-insulin receptor binding mechanisms also play a role in the enhanced response of the insulin-dependent pathway for stimulation of glucose transport in unweighted skeletal muscle and 2) indicate that IGF-I action on glucose transport is included in this enhanced response in unweighted muscle.",
keywords = "2-deoxyglucose uptake, insulin, insulin- like growth factor I, phospholipase C, simulated weightlessness, soleus, vanadate",
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AU - Henriksen, Erik J

AU - Ritter, Leslie S

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AB - We have previously demonstrated that mechanical unweighting of the soleus muscle by hindlimb suspension leads to increases in insulin receptor binding, muscle/fat-specific glucose transporter (GLUT-4) protein levels, and insulin- stimulated glucose transport activity. The present study used a novel approach to further evaluate the potential role of postreceptor binding mechanisms in this enhanced insulin effect after unweighting. Insulin-like growth factor I (IGF-I), vanadate, and phospholipase C were used to stimulate glucose transport activity independently of insulin receptor binding. Soleus glucose transport activity (assessed by 2-deoxyglucose uptake) was evaluated in vitro with soleus strips (~18 mg). Progressively increased responses to maximally effective doses of insulin or IGF-I were observed after 3 and 6 days of unweighting compared with weight-matched control strips. Enhanced maximal responses to vanadate (6 days only) and phospholipase C (3 and 6 days) for 2-deoxyglucose uptake were also observed. The results of this study 1) provide evidence that post-insulin receptor binding mechanisms also play a role in the enhanced response of the insulin-dependent pathway for stimulation of glucose transport in unweighted skeletal muscle and 2) indicate that IGF-I action on glucose transport is included in this enhanced response in unweighted muscle.

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KW - phospholipase C

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KW - vanadate

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