The myocardial profile of the cytosolic isozymes of creatine kinase is apparently not related to cyanosis in congenital heart disease.
BACKGROUND
CKMB, the cardiac-specific heterodimer of cytosolic creatine-kinase (CK), is developmentally and physiologically regulated, tissue hypoxia being a proposed regulator. In patients with cyanotic heart disease the myocardium is perfused with partially saturated blood. We questioned whether the myocardium of cyanotic subjects contains higher proportions of CKMB.


METHODS
CK activity, the distribution of cytosolic CK isozymes, activity of lactic dehydrogenase (LDH), and tissue protein content were determined in obstructive tissues removed at corrective surgery of patients with congenital heart defects. Cyanotic (n = 13) and acyanotic (n = 12) subjects were compared.


RESULTS
In cyanotic and acyanotic patients, CK activity was 8.4 +/- 0.6 and 7.6 +/- 0.6 IU/mg protein and the proportion of CKMB was 21 +/- 1.4 and 22 +/- 2. 0% (mean +/- S.E.M), respectively. In the two groups of patients, the activity related to the B subunit corresponded to the steady-state level of the CKBmRNA. The tissue content of protein and the activities of CK and LDH were similar in cyanotic and acyanotic subjects and increased with the age.


CONCLUSIONS
The lack of difference in CKMB distribution between the cyanotic and acyanotic patients may either indicate that hypooxygenation is not a regulator of CK isozyme expression, or may be attributed to the already high proportion of this isozyme in hypertrophied, obstructive tissues. Recruitment of additional CKMB, in the cyanotic hearts, may thus not be required.
Kessler-Icekson
G
G
Basil and Gerald Felsenstein Medical Research Center, The Rabin Medical Center, Petach Tikva, Israel. icekson@post.tau.ac.il
Birk
E
E
Schlesinger
H
H
Barhum
Y
Y
Ad
N
N
Friedman
M
M
Vidne
B A
BA
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001706:Biopsy; D006332:Cardiomegaly; D002648:Child; D003402:Creatine Kinase / Q000235:genetics / Q000378:metabolism*; D003490:Cyanosis / Q000201:enzymology / Q000209:etiology*; D003600:Cytosol / Q000201:enzymology*; D006330:Heart Defects, Congenital / Q000150:complications* / Q000201:enzymology* / Q000601:surgery; D006345:Heart Septal Defects, Ventricular / Q000201:enzymology / Q000601:surgery; D006352:Heart Ventricles / Q000002:abnormalities; D006801:Humans; D007527:Isoenzymes; D009206:Myocardium / Q000201:enzymology* / Q000473:pathology; D013771:Tetralogy of Fallot / Q000201:enzymology / Q000601:surgery
D007527:Isoenzymes; D003402:Creatine Kinase