Aquaporin 4: lack of mRNA expression in the rat regenerating muscle fiber under denervation

The recently identified water channel aquaporin 4 is a major component of t he orthogonal arrays observed with freeze-fracture electron microscopy, We examined the expression of aquaporin 4 mRNA and protein in rat regenerating muscle under innervated and denervated conditions. We found decreased sarc olemmal immunostaining of aquaporin 4 in denervated regenerating muscle as opposed to innervated muscle, Quantitative reverse transcription-polymerase chain reaction revealed that aquaporin 4 mRNA was expressed in the innerva ted regenerating muscle; whereas it was not expressed in denervated muscle. Thus, lack of aquaporin 4 protein may be due to lack of aquaporin 4 mRNA i n the denervated regenerating muscle. We conclude that the nerve supply inf luences expression of aquaporin 4 at the mRNA level in regenerating muscle, (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.