Effect of mechanical traumatization on rate and constancy of oxygen uptake of isolated diaphragms

Diaphragms of mice were traumatized by division parallel or transversally to the muscle fibres. The extent of traumatization was varied by the degree of subdivision. Oxygen uptake was measured by the Warburg technique. Undivided diaphragms as control displayed constant oxygen uptake for the four hours of observation. With divided diaphragms oxygen uptake was unstable. Division parallel to the muscle fibres resulted in continuous decrease of oxygen uptake after a normal initial phase; the decline was significantly steeper was increasing extent of traumatization. Division transversally to the muscle fibres resulted in an initial increase of oxygen uptake followed in a second phase by a continuous decrease. The initial increase as well as the final decrease of oxygen uptake was more pronounced with higher extent of subdivision.