During successful and uncomplicated angioplasty (PTCA), we studied the effect of a short lasting myocardial ischemia on plasma creatine kinase, creatine kinase MB-activity, and creatine kinase MM-isoforms (MM1, MM2, MM3) in 23 patients. Eleven patients, in whom diagnostic coronary angiography was performed, served as the control group. Blood was sampled after PTCA and every 2 h for the next 12 h, and after 24 h. CK- and CK-MB activities were determined enzymatically, the MM-isoforms by isoelectric focussing. After PTCA total CK and CK-MM3 increased significantly from 23 +/- 10 to 40 +/- 31 U/I (p less than 0.01) and from 18 +/- 5 to 32 +/- 10% (p less than 0.0005), respectively. The ratio MM3:MM1 also increased significantly from 0.4 +/- 0.1 to 1.2 +/- 0.7 (p less than 0.0005). Enzyme maxima for CK-MM3 and the ratio MM3:MM1 were reached 6 h after PTCA, for total CK 10 h after PTCA. This increase was independent of changes in the ECG, of symptoms during PTCA, as well as of the number and duration of balloon inflations. In the control group no changes in enzyme activity were found. Thus, after uncomplicated PTCA a significant increase of total CK and CK-MM-isoforms can be found, which may be due to the short-lasting myocardial ischemia following coronary occlusion.