Evaluation of the new Beckman electrophoretic method for CK-MB: comparison with ion exchange chromatography and investigation of a reference outpatient population

Creatine kinase, energy reserve, and hypertension: from bench to bedside

We hypothesized that human variation in the activity of the ATP regenerating enzyme creatine kinase (CK) activity affects hypertension and cardiovascular disease risk. CK is tightly bound close to ATP-utilizing enzymes including Ca2+-ATPase, myosin ATPase, and Na+/K+-ATPase, where it rapidly regenerates ATP from ADP, H+, and phosphocreatine. Thus, relatively high CK was thought to enhance ATP-demanding processes including resistance artery contractility and sodium retention, and reduce ADP-dependent functions. In a series of studies of our group and others, CK was linked to hypertension and bleeding risk. Plasma CK after rest, used as a surrogate measure for tissue CK, was associated with high blood pressure and failure of antihypertensive therapy in case-control and population studies. Importantly, high tissue CK preceded hypertension in animal models and in humans, and human vascular tissue CK gene expression was strongly associated with clinical blood pressure. In line with this, CK inhibition substantially reduced the contractility of human resistance arteries ex vivo. We also presented evidence that plasma CK reduced ADP-dependent platelet aggregation. In subsequent intervention studies, the oral competitive CK inhibitor beta-guanidinopropionic acid (GPA) reduced blood pressure in spontaneously hypertensive rats (SHRs), and a 1-week trial of sub-therapeutic dose GPA in healthy men was uneventful. Thus, based on theoretical concepts, evidence was gathered in laboratory, case-control, and population studies that high CK is associated with hypertension and with bleeding risk, potentially leading to a new mode of cardiovascular risk reduction with CK inhibition.

Serum Creatine Kinase-MB Isoenzyme Activity among Subjects with Uncomplicated Essential Hypertension: Any Sex Differences

Hypertension (high blood pressure) is a major health challenge and more women than men are affected by the condition. Complications as a result of this condition often lead to disabilities and premature death. The objective of this study was to evaluate creatine kinase-MB (CK-MB) activity in uncomplicated hypertension and to know whether sex differences exist in the activity of the enzyme. Serum creatine kinase-MB isoenzyme activity, troponin I, and lipid profile were evaluated in 140 male and 100 female Nigerians with hypertension. The control group was comprised of 100 (50 males and 50 females) normotensive subjects. Measured parameters were assayed using Selectra Pros chemistry analyzer. The means were compared between males and females using Students't-test. The mean CK-MB activity of the female hypertensive subjects was significantly higher (p < 0.001) than the males. Similarly, the mean cardiac troponin I (cTnI) of the female hypertensive subjects was significantly higher (p < 0.001) than the males. Conversely, the mean CK-MB activity of the female normotensive subjects was significantly lower (p < 0.001) than the male counterparts. There was no difference in the levels of cTnI between male and female normotensive subjects. Serum CK-MB activity was higher in female than male hypertensive subjects. In the light of these results, cardiac markers should be routinely done in the evaluation of hypertensive subjects and sex-specific consideration may be recognized in the management of these patients.

Creatine kinase is associated with failure of hypertension treatment

BACKGROUND

Failure of hypertension treatment is a major clinical issue because of the high prevalence and the associated mortality risk. We have reported evidence that creatine kinase increases blood pressure through greater sodium retention and cardiovascular contractility, by rapidly providing ATP for these functions. Therefore, we hypothesized that high creatine kinase is associated with failure of antihypertensive treatment.

METHOD

We analyzed a cross-sectional, random multiethnic sample of the general population (N = 1444), aged 34-60 years. The primary outcome was the independent association between resting serum creatine kinase and treated uncontrolled hypertension in the population, using multinomial logistic regression analysis.

RESULTS

Hypertension prevalence was, respectively, 26.8; 30.8; and 41.2% for the lowest (<88  IU/l) through the highest population creatine kinase tertile (>145  IU/l; P < 0.001). Treatment failed in 72.9% of participants within the highest creatine kinase tertile vs. 46.7% within the lowest tertile (P = 0.004). In logistic regression analysis, creatine kinase was the main predictor of treatment failure (adjusted odds ratio 3.7; 95% confidence interval 1.2-10.9), independent of age, sex, BMI, fasting glucose, ethnicity, or education level.

CONCLUSION

Creatine kinase is associated with failure of antihypertensive therapy. Further investigations concerning this association might help improve treatment strategies for difficult-to-treat hypertension.

Creatine kinase activity is associated with blood pressure

BACKGROUND

We previously hypothesized that high activity of creatine kinase, the central regulatory enzyme of energy metabolism, facilitates the development of high blood pressure. Creatine kinase rapidly provides adenosine triphosphate to highly energy-demanding processes, including cardiovascular contraction, and antagonizes nitric oxide-mediated functions. Relatively high activity of the enzyme, particularly in resistance arteries, is thought to enhance pressor responses and increase blood pressure. Tissue creatine kinase activity is reported to be high in black people, a population subgroup with greater hypertension risk; the proposed effects of high creatine kinase activity, however, are not "race dependent." We therefore assessed whether creatine kinase is associated with blood pressure in a multiethnic population.

METHODS AND RESULTS

We analyzed a stratified random sample of the population of Amsterdam, The Netherlands, consisting of 1444 citizens (503 white European, 292 South Asian, 580 black, and 69 of other ethnicity) aged 34 to 60 years. We used linear regression analysis to investigate the association between blood pressure and normal serum creatine kinase after rest, as a substitute measure of tissue activity. Creatine kinase was independently associated with blood pressure, with an increase in systolic and diastolic pressure, respectively, of 8.0 (95% CI, 3.3 to 12.7) and 4.7 (95% CI, 1.9 to 7.5) mm Hg per log creatine kinase increase after adjustment for age, sex, body mass index, and ethnicity.

CONCLUSIONS

Creatine kinase is associated with blood pressure. Further studies are needed to explore the nature of this association, including how variation in cardiovascular creatine kinase activity may affect pressor responses.

Quantitation of creatine kinase MB using an agarose electrophoresis method; importance of enzyme reagent concentration

Quantification of CK-MB activity in serum using agarose electrophoresis requires that CK enzyme reagent be layered over the gel in order to develop enzyme activity. We have shown that when commercial enzyme reagents were used, and reconstituted in a normal fashion, that the CK-MM isoenzyme activity is underestimated which results in an overestimation of CK-MB activity. Underestimation of CK-MM occurs because the enzyme reagent are diluted approximately five-fold by the agarose, which results in the non-linear development of enzyme activity under sub-optimal conditions. Reconstitution of these commercial enzyme reagents in a concentrated manner (5 times more concentrated) compensates for the dilution of the reagent by the agarose and allows for the linear development with time of CK-MM and CK-MB enzyme activity. However, use of five-fold concentrated enzyme reagent does not totally prevent underestimation of CK-MM enzyme activity, and care must be taken in limiting the amount of enzyme activity placed on the agarose gel.