High-energy phosphotransfer in the failing mouse heart: role of adenylate kinase and glycolytic enzymes

Abstract

Aims: To measure the activity of the key phosphotransfer enzymes creatine kinase (CK), adenylate kinase (AK), and glycolytic enzymes in two common mouse models of chronic heart failure.

Methods and results: C57BL/6 mice were subjected to transverse aortic constriction (TAC), myocardial infarction induced by coronary artery ligation (CAL), or sham operation. Activities of phosphotransfer enzymes CK, AK, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 3-phosphoglycerate kinase (PGK), and pyruvate kinase were assessed spectrophotometrically. Mice were characterized by echocardiography or magnetic resonance imaging 5- to 8-week post-surgery and selected for the presence of congestive heart failure. All mice had severe left ventricular hypertrophy, impaired systolic function and pulmonary congestion compared with sham controls. A significant decrease in myocardial CK and maximal CK reaction velocity was observed in both experimental models of heart failure. However, the activity of AK and its isoforms remained unchanged, despite a reduction in its protein expression. In contrast, the activities of glycolytic phosphotransfer mediators GAPDH and PGK were 19 and 12% higher in TAC, and 31 and 23% higher in CAL models, respectively.

Conclusion: Chronic heart failure in the mouse is characterized by impaired CK function, unaltered AK, and increased activity of glycolytic phosphotransfer enzymes. This pattern of altered phosphotransfer activity was observed independent of the heart failure aetiology.

Figure 1

Adenylate kinase and creatine kinase activity in transverse aortic constriction heart failure. AK, total adenylate kinase; AK₁, AK 1 isoform; AK_rem, remnant AK isoforms (i.e. AK_2,3,6). Data presented as mean ± SD. Sham n = 8, transverse aortic constriction n = 12. *P < 0.05 vs. sham controls.

Figure 2

(A) AK₁ mRNA level in transverse aortic constriction heart failure, (B) AK₁ total protein expression in transverse aortic constriction heart failure, (C) AK₁ mRNA level in coronary artery ligation heart failure, and (D) AK₁ total protein expression in coronary artery ligation heart failure. mRNA levels are expressed in arbitrary units. Transverse aortic constriction sham n = 3, transverse aortic constriction n = 4, coronary artery ligation sham n = 3, coronary artery ligation n = 4. AK₁ optical density values are normalized against α-actinin and expressed as the relative change to the sham set as 1. The optical density values used for each experimental group are the average of three independent western blot experiments. Transverse aortic constriction sham n = 6, transverse aortic constriction n = 7, coronary artery ligation sham n = 5, coronary artery ligation n = 5. Data presented as mean ± SD. *P < 0.05 vs. sham controls.

Figure 3

Glycolytic enzyme activities in transverse aortic constriction heart failure. GAPDH, PGK, and PK: sham n = 8, transverse aortic constriction n = 12; hexokinase n = 4. Data presented as mean ± SD. *P < 0.05 vs. sham controls.

Figure 4

Adenylate kinase and creatine kinase activity in coronary artery ligation heart failure. AK, total adenylate kinase; AK₁, AK 1 isoform, AK_rem, remnant AK isoforms (i.e. AK_2,3,6). Sham n = 6–12, coronary artery ligation n = 13–14. Data presented as mean ± SD. *P < 0.05 vs. sham controls.

Figure 5

Glycolytic enzyme activities in coronary artery ligation heart failure. Sham n = 7–9, coronary artery ligation n = 12–14. Data presented as mean ± SD. *P < 0.05 vs. sham controls.

Figure 6

Relationship between creatine kinase and phosphoglycerate kinase activities in mice with congestive heart failure (transverse aortic constriction and coronary artery ligation) (r = −0.511 P < 0.005).