Dantrolene inhibits halothane-induced membrane reorganization A study using 31P-NMR and differential scanning calorimetry

Abstract

The action of the relaxing agent dantrolene on dipalmitoylphosphatidylcholine (DPPC) model membranes in the presence and absence of the general anesthetic halothane has been investigated by DSC and 31P-NMR. Dantrolene has a weak effect on both the thermodynamic and NMR parameters of the pure model membrane. When halothane is present in the system, the relaxing agent acts to counterbalance the strong anesthetic-induced membrane perturbation. This is reflected in DSC experiments by a change of the enthalpy variation (delta H) and of the main gel-to-fluid phase transition temperature (Tc) towards the values of the pure lipid system. The amount of halothane-induced small tumbling vesicles, as detected by 31P-NMR by the superposition of an isotropic line on a lamellar-type powder spectrum, is considerably reduced upon dantrolene addition. This means that the relaxing agent "cures" the membrane de-structuring action promoted by halothane. Membranes first treated with dantrolene are also protected from the halothane perturbation. So, the relaxing agent is both "curative" and "preventative" against halothane. The optimum effect is obtained for 1 dantrolene molecule per ca 34 halothane molecules. The mechanisms of action were discussed in relation to membrane fluidity.

New amphiphilic derivatives of cyclodextrins for the purpose of insertion in biological membranes: the “Cup and Ball” molecules

“…In the latter cases, the disappearance of the pre-transition peak and the important broadening of the transition peak are characteristic of the incorporation phenomenon which represents a perturbation of the lipidic matrix and loss of cooperativity. 26 The temperatures of the pre-transition and transition and the value of the enthalpy were determined for each sample. The main results are displayed in Table 2.…”