Contractile properties of rat skeletal muscles following storage at 4 °C

The purpose of this study was to assess the potential of preservation solutions for protecting skeletal muscle function during storage at 4 °C. The soleus and the cutaneus trunci (CT) from the rat were stored for 2, 8 or 16 h at 4 °C in University of Wisconsin solution (UW), HTK–Bretschneider solution (HTK) or Krebs–Henseleit solution (KH). After storage, muscles were stimulated electrically to analyse the isometric contractile properties, such as the maximum tetanic tension (P₀). Histological analysis was also performed. In separate experiments, the effect of the diffusion distance on muscle preservation was studied by bisecting the soleus. After 8 h of storage in UW or HTK, the contractile properties of the CT were similar to those of the control, whereas those of the soleus were reduced (P₀ values of 16% and 69% of control in UW and HTK respectively). At 16 h, the contractile properties of the CT (P₀ 28%) were again better preserved than those of the soleus (P₀ 9%). Muscle function deteriorated most after storage in KH (P₀ at 16 h: soleus, 3%; CT, 17%). The bisected soleus was equally well preserved as the CT (P₀ of bisected soleus at 8 h in UW and HTK: 86%). The functional data corresponded well with the histological data, which showed increasing muscle fibre derangement with increasing storage time. For both muscles and all solutions, the threshold stimulus current increased with increasing storage time (control, 0.1 mA; 16 h, 1.2 mA) and was strongly correlated with the deterioration in contractile properties. It is concluded that, at 4 °C, muscle is preserved better in UW and HTK (intracellular-like solutions) than in KH (extracellular-like solution). The soleus and CT were best protected in HTK. The diffusion distance is a critical factor for successful preservation of muscle function at 4 °C. The reduced function after 16 h of storage at 4 °C was caused by hypercontraction and necrosis of about 25% of the muscle fibres, and by deterioration of the electrical component of excitation–contraction coupling of the remaining fibres.