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Angiotensin mediates forearm glucose uptake by hemodynamic rather than direct effects
K A Jamerson1, S D Nesbitt, J V Amerena
1Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, 48109-0356, USA.
Hypertension (Dallas, Tex. : 1979)
|April 1, 1996
Summary
Local infusion of angiotensin II (Ang II) into human skeletal muscle did not impair insulin-stimulated glucose uptake. Ang II infusion decreased blood flow, but glucose extraction increased, suggesting hemodynamic factors, not direct metabolic effects, influence glucose utilization.
Area of Science:
- Endocrinology
- Cardiovascular Physiology
- Metabolic Research
Background:
- Angiotensin II (Ang II) and ACE inhibitors have complex effects on glucose metabolism.
- Both systemic Ang II administration and ACE inhibition can improve glucose utilization.
- The direct impact of Ang II on skeletal muscle glucose uptake is not well understood.
Purpose of the Study:
- To investigate the direct effects of local angiotensin II (Ang II) infusion on glucose uptake in human skeletal muscle.
- To determine if Ang II directly modulates insulin-stimulated glucose utilization in the forearm.
Main Methods:
- Utilized the isolated insulin-perfused forearm model in 20 healthy subjects.
- Administered local intra-arterial infusion of Ang II during a 90-minute insulin clamp (100 mU/mL).
- Measured forearm blood flow and arteriovenous glucose gradients to assess glucose utilization.
Main Results:
- Intra-arterial Ang II infusion decreased forearm blood flow by 38% (P <.05).
- Arteriovenous glucose gradients increased by 59% (P <.05), maintaining steady glucose utilization.
- Local Ang II infusion did not impair insulin-stimulated glucose utilization; glucose extraction compensated for reduced blood flow.
Conclusions:
- Local angiotensin II (Ang II) infusion does not directly impair insulin-stimulated glucose utilization in human skeletal muscle.
- Increased glucose utilization observed with systemic Ang II or ACE inhibitors is likely mediated by hemodynamic changes, not direct metabolic effects.
- Hemodynamic factors, such as altered blood flow and subsequent glucose extraction, play a crucial role in modulating glucose uptake in skeletal muscle.