An in vitro study of the effects of venom of Australian elapids on murine skeletal muscle and the protective effect of homologous plasma

The venom of many dangerous Australian snakes has a myotoxic component and some are strongly myolytic. The myotoxicity of venom of seven Australian elapid snakes was studied to determine their relative in vitro potency in causing cell death of C2C12 cells, a myoblast cell line, and murine pmyotubes in mixed cell culture. The venom of Pseudechis australis proved to be most myotoxic, Austrelaps superbus and Pseudechis porphyriacus venoms also exhibited myotoxicity relative to the other venoms tested. The specificity of Pseudechis porphyriacus venom was tested using the human glioma cell line TC3 and was shown to exhibit a general cytotoxicity. Myotoxicity, however, was the predominant action of the venom. It has long been known that certain animals sucha as the mongoose (herpestes edwardsii) are able to survive envenomation. Some species of snakes also possess this property and the neutralising factor(s) responsible for this P. porphyriacus has been shown to be present in the serum. The protective effect of homologous plasma from P. porphyriacus venom was also studied with reference to myotoxicity and cytotoxicity. The results of this study clearly demonstrated protection by homologous plasma using a myoblast cell line, C2C12, a primary mixed cell culture and TC3 cells. While protection was clear, particularly using high concentrations of venom, it was not absolute, and homologous plasma did not afford continued protection from the effects of the venom. In the mixed culture experiments venom/plasma mixtures pre-incubated for 30 min were more protective than venom/plasma mixtures which were not incubated, in contrast to the results of cell culture studies, which showed little difference.

Effects of preconditioning protocols on canine latissimus dorsi muscle

This reporti is a review of numerous protocols that have been used for conditioning of the latissimus dorsi muscle (LDM) for use in cardiomyoplasty. In this study the LDM of mongrel dogs was freed stretched about 1.5 cm and the distal end sutured to the iliac crest. Eleven preconditioining protocols were undertaken using the following technique: stretch, stretch + single pulse stimulation pulse stimulation 45-7--100/min, strech + single stimulation 70-90/min, transection of left teres major (TM), Ttransection + single stimulation 45-75-100/min, subscapularis nerve crush, subscapularis nerve crush + intercostal vessel cut + stimulation 45-70-100/min, subscapularis nerve crush + intercostal or 100/min. A variety of pacemakers were used. Upon sacrifice at 3,4,6,8,16 or 28 weeks, LDMs were removed, wighed and assessed hitologically. In all of the muscles that were subjected to eletrical stimulation alone, atrophy resulted. Our experiments using increased workload and electrical stimulation at variousrtes resulted in conversion of fast to slow fiber types and less fibrosis and adiposis than stimulation alone. Unless a means can be developed to avoid atrophy of the LDM when it is used in the cardiomyoplasty procedure, poor results may be anticipated from the operation.