Transmurally differentiated measurement of ATP hydrolysis rates in the in vivo porcine hearts. Issue 5 (19th February 2016)

• Record Type: Journal Article
• Authors: Jang, Albert; Xiong, Qiang; Zhang, Pengyuan; Zhang, Jianyi
• Is Part Of: Magnetic resonance in medicine. Volume 75:Issue 5(2016)
• Page Start: 1859
• Page End: 1866
• Publication Date: 2016-02-19
• Subjects: heart -- magnetic resonance spectroscopy -- saturation transfer -- high‐energy phosphate -- ATP hydrolysis rate; Nuclear magnetic resonance -- Periodicals; Electron paramagnetic resonance -- Periodicals; 616.07548
• DOI: 10.1002/mrm.26162
• Languages: English
• ISSNs: 0740-3194

Abstract

Abstract : Purpose: Compare the transmural distribution of forward creatine kinase reaction ( k f, CK ) and ATP hydrolysis rate ( k r, ATPase ) in the myocardium of normal porcine heart. Rate constants were extracted from partially relaxed spectra by applying the T 1 nom method, effectively reducing data acquisition time by up to an order of magnitude. Theory and Methods: T 1 nom method for double saturation of PCr and Pi is introduced and validated through simulations. Bioenergetics was measured in vivo utilizing one‐dimensional chemical shift imaging (1D‐CSI) magnetic resonance 31 P spectroscopy. Results: At basal conditions, there was no significant difference between subepicardial layers (EPI) vs. the subendocardial layers (ENDO) for both flux f, CK and flux r, ATPase . At high cardiac workload (HWL), where the rate pressure product increased 2.6‐fold, PCr/ATP ratio and flux f, CK showed no significant change in both EPI and ENDO layers, while flux r, ATPase increased significantly (baseline: 1.11 ± 0.12 and 1.12 ± 0.13 μmol/g/s, EPI and ENDO, respectively; to HWL: 2.35 ± 0.27 and 2.21 ± 0.08 μmol/g/s, EPI and ENDO, respectively, each P < 0.01 vs. baseline). Conclusion: In the normal heart, increase of cardiac work state is accompanied by an increase in ATP hydrolysis rate with no changes in CK flux rate. There are no significant differences between EPI vs. ENDO concerning the ATP hydrolysis rate or CK flux rate in both baseline and high cardiac work states. Magn Reson Med 75:1859–1866, 2016. © 2016 Wiley Periodicals, Inc.