Cardiac troponin T and creatine kinase MB content in skeletal muscle of the uremic rat.
BACKGROUND
The assertion that creatine kinase MB (CK-MB) and the developmental isoforms of cardiac troponin T (cTnT) are expressed by skeletal muscle in some clinical settings is an extrapolation from nonuremic rodent studies. We studied the content of CK-MB and cTnT in skeletal muscle of the renal-insufficient rat.


METHODS
Skeletal muscles (gastrocnemius) were collected from both five-sixths nephrectomized rats (n = 11) and sham-operated controls (n = 11). cTnT content was analyzed by Elecsys (Roche), immunoblotting, and immunohistochemistry with antibodies M7 and M11-7 (Roche). CK isoenzymes were analyzed electrophoretically.


RESULTS
Trace concentrations of cTnT were detected in some of the skeletal muscle samples [controls (3 of 11) and uremic rats (1 of 11)] at concentrations <0.01% of that detected in heart. By contrast, positive staining appeared in both groups with M11-7 by immunoblotting and immunohistochemistry. No immunoreactivity was detected in skeletal muscle using M7 in the immunoblot format, although immunoreactivity was detected by immunohistochemistry in all samples. The median percentages of CK-MB were 6.0% and 4.1% for the skeletal muscle from control and uremic rats, respectively.


CONCLUSIONS
The detection of cTnT and CK-MB in skeletal muscle does not differ for uremic rats compared with sham-operated controls. cTnT isoforms detected by qualitative methods are not detected with the cTnT immunoassay. Observations with rodents should not necessarily be extrapolated to humans.
Fredericks
Salim
S
Analytical Unit, Cardiological Sciences, St. George's Hospital Medical School, London SW17 0RE, United Kingdom. frederic@sghms.ac.uk
Murray
Joanne F
JF
Carter
Nicholas D
ND
Chesser
Alistair M S
AM
Papachristou
Stavroula
S
Yaqoob
Magdi M
MM
Collinson
Paul O
PO
Gaze
David
D
Holt
David W
DW
D000818:Animals; D015153:Blotting, Western; D003402:Creatine Kinase / Q000378:metabolism*; D052279:Creatine Kinase, MB Form; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D009392:Nephrectomy; D051381:Rats; D017208:Rats, Wistar; D020107:Troponin T / Q000378:metabolism*; D014511:Uremia / Q000201:enzymology / Q000378:metabolism*
D007527:Isoenzymes; D020107:Troponin T; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form