Anesthesiology
-
Recent work suggests that impaired Mg(2+) regulation of the ryanodine receptor is a common feature of both pig and human malignant hyperthermia. Therefore, the influence of [Mg(2+)] on halothane-induced Ca(2+) release from the sarcoplasmic reticulum was studied in malignant hyperthermia-susceptible (MHS) or -nonsusceptible (MHN) muscle. ⋯ When Mg(2+) inhibition of the ryanodine receptor is reduced, the halothane sensitivity of MHN fibers and the characteristics of the Ca release process approach that of the MHS phenotype. In MHS fibers, reduced Mg(2+) inhibition of the ryanodine receptor would be expected to have a major influence on halothane sensitivity. The Mg dependence of the halothane response in MHN and MHS may have important clinical implications in circumstances where intracellular [Mg(2+)] deviates from normal physiologic concentrations.
-
The concentration of peroxynitrite in the brain increases after central nervous system injuries. The authors hypothesized that propofol, because of its particular chemical structure, mitigates the effects of peroxynitrite-mediated oxidative stress and apoptosis by the induction of heme oxygenase (HO)-1 in primary cultured astroglial cells. ⋯ The antioxidant properties of propofol can be partially attributed to its scavenging effect on peroxynitrite as well as to its ability to increase HO-1 expression at higher concentrations, a property that might be relevant to neuroprotection during anesthesia.