Metabolism of perfused pig intercostal muscles evaluated by 31 P‐magnetic resonance spectroscopy

• Published in: Experimental physiology 2006-07, Vol.91 (4), p.755-763
• Main Authors: Pedersen, Brian Lindegaard, Arendrup, Henrik, Secher, Niels H., Quistorff, Bjørn
• Format: Article
• Language: English
• ISSN: 0958-0670; 1469-445X
• DOI: 10.1113/expphysiol.2006.033274

This study presents a perfused preparation for evaluation of metabolism in pig intercostal muscle in vitro . Preserved vessels and nerves to an intercostal segment including two adjacent ribs allowed for tissue perfusion and electrical stimulation with measurement of contraction force, oxygen consumption and 31 P‐magnetic resonance spectroscopy ( 31 P‐MRS). When perfused at rest with Krebs–Ringer buffer, the preparation maintained physiological levels of phosphocreatine (PCr), inorganic phosphate (P i ), ATP and pH at a stable oxygen consumption of 0.51 ± 0.01 μmol min −1 g −1 for more than 2 h. Tonic stimulation of the nerve caused anaerobic energy consumption as PCr and pH decreased, and both variables recovered after the contraction with half‐time values of ∼7 min. Force increased to 0.040 N g −1 (range, 0.031–0.103 N g −1 ) and it gradually decreased by about 70% during the subsequent 5 min of stimulation. The calculated free ADP concentration increased from 7.4 ± 2.1 nmol g −1 at rest to 28 ± 12 nmol g −1 (mean ± s.d. ) by the end of the stimulation. Thus anaerobic ATP turnover was zero at rest, 6.1 ± 2 μmol min −1 g −1 during the first minute of stimulation and 3.5 ± 0.5 μmol min −1 g −1 during the two last minutes, corresponding to the drop in force. When the preparation was left unperfused, anaerobic ATP turnover averaged 0.40 ± 0.15 μmol min −1 g −1 for the first 10 min. The preparation can also be applied to human intercostal muscles, as demonstrated in one preliminary experiment. The results demonstrate a stable and functional in vitro preparation of intact perfused intercostal muscles in the pig.