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Transcapillary insulin transfer in human skeletal muscle
H Herkner1, N Klein, C Joukhadar
1Department of Clinical Pharmacology, University of Vienna, Medical School, Vienna, Austria.
European Journal of Clinical Investigation
|February 18, 2003
Summary
Transcapillary insulin transfer in skeletal muscle is a saturable process. This finding suggests it partly limits insulin action even under physiological conditions, impacting glucose metabolism.
Area of Science:
- Endocrinology
- Metabolic Research
- Physiology
Background:
- Transcapillary insulin transfer is crucial for insulin action, especially at high concentrations.
- Its role in physiological conditions remains incompletely understood.
- Understanding this process is key to metabolic regulation.
Purpose of the Study:
- To characterize transcapillary insulin transfer in human skeletal muscle under physiological conditions.
- To investigate insulin gradients between plasma and interstitial fluid.
- To determine if transcapillary insulin transport is a rate-limiting step.
Main Methods:
- In vivo microdialysis of skeletal muscle in eight healthy lean males.
- Measurement of insulin concentrations in plasma and interstitial fluid.
- Utilized oral glucose tolerance test and euglycaemic hyperinsulinaemic clamp.
Main Results:
- Baseline interstitial insulin was significantly lower than plasma insulin (19 vs. 48 pmol/L).
- The interstitial to plasma insulin ratio remained stable during oral glucose tolerance test.
- This ratio significantly decreased under euglycaemic hyperinsulinaemic clamp conditions (0.12).
Conclusions:
- A substantial transcapillary insulin gradient exists in human skeletal muscle.
- Findings support saturable transcapillary insulin transport.
- This transport is a partly rate-limiting step for insulin action.