Using 31P NMR and the saturation-transfer method, the unidirectional rate of ATP synthesis was measured in isolated, Langendorff-perfused, isovolumic rat hearts operating at a rate pressure product of 25.6 ± 2.5 (SE) × 103 mmHg · min-1 and consuming O2; at a rate of 35 ± 2 μmol O2 · min-1. (g dry wt)-1, at 37°C. This rate was 7.2 ± 0.9 μmol · s-1 · (g dry wt)-1 and was related to the rate of oxygen atom consumption by a ratio of 6.3 ± 0.9. These date show that in the intact heart the unidirectional rate of ATP synthesis exceeds the net rate of ATP synthesis and consumption by approximately a factor of 2.
Bibliographical noteFunding Information:
This researchw as supported by NIH grants fK04 HL01241, ROl HL33600 and ROI HL26640, VeteransA dministrationM edical ResearchF unds, and Karl-Thomae GmbH (Biberach an der Riff, FRG).
- ( Rat myocardium)
- Saturation transfer