Investigations of thermotropic phase changes in peripheral nerve of frog and rat. A spin label study.
The temperature-dependent fluidity of myelin of frog and rat peripheral nerve (Nervus ischiadicus) was studied using the spin label technique. In frog nerve a phase change was detected at 38 degree C. In rat nerve no sharp phase change could be established, and the lipid-depleted frog and rat nerve also showed no transition. From the spectral data, it was concluded that in frog and rat nerve the lipid-protein interactions are different, i.e. species dependent. Ca-2+-depletion of frog nerve caused a loss of transition, while rat nerve remained unaffected. Thus it was indicated that, in frog nerve, Ca-2+ is involved in the phase change. In the total lipid extract of frog nerve a phase change centered at 32 degree C occurred, while the total lipid extract of rat nerve again showed no transition. It is suggested that a connexion exists between our results and investigations on the temperature dependence of an axonal conduction block of nerve.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D005227:Fatty Acids / Q000032:analysis; D008055:Lipids / Q000032:analysis; D009186:Myelin Sheath / Q000032:analysis / Q000187:drug effects / Q000502:physiology; D010525:Peripheral Nerves / Q000032:analysis* / Q000187:drug effects / Q000502:physiology; D011896:Rana temporaria; D051381:Rats; D013113:Spin Labels; D013229:Stearic Acids; D013696:Temperature
D005227:Fatty Acids; D008055:Lipids; D013113:Spin Labels; D013229:Stearic Acids; D002118:Calcium