Creatine kinase isoenzyme activity in human placenta and in serum of women in labor.

Creatine kinase (EC 2.7.3.2) isoenzymes in extracts of human placenta and in serum from nonpregnant women and women in labor were separated on columns containing diethylaminoethyl-cellulose and assayed. The distribution of the isoenzymes in placenta (n = 10) was 80% BB (200 +/- 66 U/g (wet weight), 19% MM (49 +/- 30 U/g), and 1% MB (2.6 +/- 1.7 U/g); The geometric mean for the serum BB activity of the nonpregnant women (n = 50) was 0.6 +/- 1.5 U/liter, as compared to 3.0 +/- 1.4 U/liter for patients in labor who had normal deliveries (n = 92). The arithmetic mean for serum BB activity of labor patients with induced labor (n = 20), premature labor (n = 7), cesarian section (n = 6), or hypertension and pre-eclampsia (n = 6) did not differ significantly from the arithmetic mean BB activity for serum of labor patients with normal deliveries. However, the arithmetic mean serum BB activity of patients with stillbirths (n = 7) was significantly smaller than the arithmetic mean for normal labor patients.