Untitled

Abstract

The question whether aquaporin 3 (AQP3) is expressed in normal human skeletal muscle at mRNA and protein levels has been examined, since AQP3 has been reported to be coexpressed with AQP4 in various kinds of tissues other than skeletal muscle. The gel electrophoresis of the reverse transcription polymerase chain reaction (RT-PCR) product of total RNA samples extracted from normal human muscle specimens by using the oligonucleotide primers for AQP3 contained a band of 629 base pairs which corresponded to the base pair length between two primers of AQP3. The nucleotide sequence of this RT-PCR product coincided with that of AQP3. At the protein level, immunoblot, immunohistochemical and immunoelectron microscopical studies were done by using rabbit antibody against the synthetic peptide of the cytoplasmic domain of the human AQP3 molecule. Immunoblot analysis showed that rabbit antibody against the human AQP3 reacted with a protein of approximately 30 kDa molecular weight in extracts of normal human skeletal muscles. The immunoreaction for the anti-AQP3 antibody with normal human muscle was noted at the myofibre surface. Immunogold labelling electron microscopy revealed that the gold particles indicating the presence of AQP3 molecules were located mainly at the inside surface of muscle plasma membrane.

Feeding Your Himalayan Expedition: Nutritional Signatures and Body Composition Adaptations of Trekkers and Porters

“…Hypoxia-inducible factors, such as HIF-1, may also regulate body fluid balance through aquaporin function [48]. The presence of aquaporins, such as AQP3, on skeletal myofibers' membrane [49], and the inducibility of the same AQP by HIF-1 [48], may support a direct role of oxygen deprivation on regulating the structure of skeletal muscles cells. The results of our study show loss of muscle mass and body fluids occurred despite an adequate intake of proteins and specific recommendation for avoiding dehydration.…”

Aquaporins and Neurodegenerative Diseases

“…However, water permeability analysis unexpectedly failed to show any differences between wild type and AQP4 knock-out mice in neuromuscular function, suggesting that AQP4 does not play a significant role in skeletal muscle physiology [57; 103]. A compensation of water channel function by other water channel proteins such as AQP3 [95] is another possibility. Further studies are needed to clarify the mechanism of transcriptional regulation by AQP proteins in denervated muscles.…”

Upregulated Expression of AQP 7 in the Skeletal Muscles of Obese ob/ob Mice

“…AQP7-deficient mice have been reported to lead to obesity [12, 13, 22], while AQP9 deletion leads to the onset of diabetes mellitus [29]. We have so far been analyzing the expression of AQPs3, 7 and 9 in human skeletal muscles and AQP7 in mouse skeletal muscles [14, 38, 39]. These three AQPs in the human skeletal muscles and AQP7 in the mouse skeletal muscles were found to be expressed at the myofiber surface of the skeletal muscle tissues, although the contradictory result has been reported with respect to AQP7 [32].…”