TY - JOUR

T1 - Expression of Na+/HCO3- co-transporter proteins (NBCs) in rat and human skeletal muscle

AU - Kristensen, Jonas Møller

AU - Kristensen, Michael

AU - Juel, Carsten

N1 - Keywords: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; Animals; Bicarbonates; Blotting, Western; Humans; Immunohistochemistry; Microscopy, Fluorescence; Muscle Fibers; Muscle, Skeletal; Protein Isoforms; Rats; Sarcolemma; Sodium-Bicarbonate Symporters

PY - 2004

Y1 - 2004

N2 - AIM: Sodium/bicarbonate co-transport (NBC) has been suggested to have a role in muscle pH regulation. We investigated the presence of NBC proteins in rat and human muscle samples and the fibre type distribution of the identified NBCs. METHODS AND RESULTS: Western blotting of muscle homogenates and sarcolemmal membranes (sarcolemmal giant vesicles) were used to screen for the presence of NBCs. Immunohistochemistry was used for the subcellular localization. The functional test revealed that approximately half of the pH recovery in sarcolemmal vesicles produced from rat muscle is mediated by bicarbonate-dependent transport. This indicates that the NBCs are preserved in the vesicles. The western blotting experiments demonstrated the existence of at least two NBC proteins in skeletal muscle. One NBC protein (approximately 150 kDa) seems to be related to the kidney/pancreas/heart isoform NBC1, whereas the other protein (approximately 200 kDa) is related to the NBC4 isoform. The two NBC proteins represent the electrogenic isoforms named NBCe1 and NBCe2. Membrane fractionation and immunofluorescence techniques confirmed that the two NBCs are located in the sarcolemmal membrane as well as in some internal membranes, probably the T-tubules. The two NBCs localized in muscle have distinct fibre type distributions. CONCLUSIONS: Skeletal muscle possesses two variants of the sodium/bicarbonate co-transporter (NBC) isoforms, which have been called NBCe1 and NBCe2.

AB - AIM: Sodium/bicarbonate co-transport (NBC) has been suggested to have a role in muscle pH regulation. We investigated the presence of NBC proteins in rat and human muscle samples and the fibre type distribution of the identified NBCs. METHODS AND RESULTS: Western blotting of muscle homogenates and sarcolemmal membranes (sarcolemmal giant vesicles) were used to screen for the presence of NBCs. Immunohistochemistry was used for the subcellular localization. The functional test revealed that approximately half of the pH recovery in sarcolemmal vesicles produced from rat muscle is mediated by bicarbonate-dependent transport. This indicates that the NBCs are preserved in the vesicles. The western blotting experiments demonstrated the existence of at least two NBC proteins in skeletal muscle. One NBC protein (approximately 150 kDa) seems to be related to the kidney/pancreas/heart isoform NBC1, whereas the other protein (approximately 200 kDa) is related to the NBC4 isoform. The two NBC proteins represent the electrogenic isoforms named NBCe1 and NBCe2. Membrane fractionation and immunofluorescence techniques confirmed that the two NBCs are located in the sarcolemmal membrane as well as in some internal membranes, probably the T-tubules. The two NBCs localized in muscle have distinct fibre type distributions. CONCLUSIONS: Skeletal muscle possesses two variants of the sodium/bicarbonate co-transporter (NBC) isoforms, which have been called NBCe1 and NBCe2.

U2 - 10.1111/j.1365-201X.2004.01297.x

DO - 10.1111/j.1365-201X.2004.01297.x

M3 - Journal article

C2 - 15329059

VL - 182

SP - 69

EP - 76

JO - Acta Physiologica

JF - Acta Physiologica

SN - 1748-1708

IS - 1

ER -