Kessler-Icekson G, Birk E, Schlesinger H, Barhum Y, Ad N, Friedman M, Vidne B A
Basil and Gerald Felsenstein Medical Research Center, The Rabin Medical Center, Petach Tikva, Israel.
Mol Med. 1999 Feb;5(2):110-6.
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.
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.
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.
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.
肌酸激酶同工酶MB（CKMB）是胞质肌酸激酶（CK）的心脏特异性异二聚体，其表达受到发育和生理调节，组织缺氧被认为是一种调节因素。在患有青紫型心脏病的患者中，心肌由部分饱和的血液灌注。我们质疑青紫型患者的心肌中是否含有更高比例的CKMB。
在先天性心脏缺陷患者矫正手术中切除的梗阻组织中，测定CK活性、胞质CK同工酶分布、乳酸脱氢酶（LDH）活性和组织蛋白含量。比较了青紫型患者（n = 13）和非青紫型患者（n = 12）。
在青紫型和非青紫型患者中，CK活性分别为8.4±0.6和7.6±0.6 IU/mg蛋白，CKMB比例分别为21±1.4%和22±2.0%（平均值±标准误）。在两组患者中，与B亚基相关的活性与CKBmRNA的稳态水平相对应。青紫型和非青紫型患者的组织蛋白含量、CK和LDH活性相似，且随年龄增加。
青紫型和非青紫型患者之间CKMB分布缺乏差异，这可能表明低氧血症不是CK同工酶表达的调节因素，或者可能归因于该同工酶在肥厚性梗阻组织中已经占很高比例。因此，青紫型心脏可能不需要额外募集CKMB。
