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Updated: Feb 17, 2026

Author Spotlight: Deciphering the Mysteries of Skeletal Muscle Fiber Types Using the MyDoBID Technique
Published on: September 22, 2023
Aquaporin 4 expression in human skeletal muscle fiber types
Elisa Vizzaccaro1, Chiara Terracciano2, Emanuele Rastelli2
1NESMOS Department, University of Rome Sapienza, Rome, Italy.
Introduction:
Aquaporins (AQPs) are a family of transmembrane proteins involved in the maintenance of osmotic gradients. AQP4 is abundant in skeletal muscle, where it seems to be associated with glycolytic metabolism. We investigated the pattern of expression of AQP4 in normal human myofibers relative to the main forms of myosin heavy chain (MHC).
Methods:
Six normal human muscle biopsies were analyzed by double immunofluorescence for co-expression of AQP4 and slow or fast MHC.
Results:
A high percentage (64-99%) of MHC-fast positive fibers showed immunoreaction for AQP4. Immunoreactivity for AQP4 was also present in MHC-slow positive fibers, but with a higher variability (5-72%) among biopsies.
Discussion:
The expression pattern of AQP4 in human myofibers is highly variable among different patients and cannot be predicted for single fibers depending on MHC type expression. Other factors, possibly related to muscle activity, may modulate AQP4 expression. Muscle Nerve 57: 856-859, 2018.
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