Myoplasmic calcium changes precede metabolic and clinical signs of porcine malignant hyperthermia.

This study examines the chronologic relationship of the biochemical and clinical development of malignant hyperthermia (MH) in susceptible swine. Four pigs previously established by challenge to be susceptible to MH were studied. Monitors included end-tidal CO2 (ETCO2), transcutaneous oxygen saturation (Spo2), intraarterial blood pressure, rectal temperature, electrocardiogram (ECG), and train-of-four twitch measurements.

EU 4093 decreases intracellular [Ca2+] in skeletal muscle fibers from control and malignant hyperthermia-susceptible swine.

The mechanisms causing the malignant hyperthermia (MH) syndrome are related to a malfunction of intracellular Ca2+ homeostasis and can be prevented or reversed by dantrolene. EU 4093 (Azumolene, 1-[[[5-(4-bromophenyl)-2-oxyzolyl] methylene]amino]-2-4- imidazolidinedione) is a 30-fold more water-soluble analogue of dantrolene that is believed to have the same effects as dantrolene on the intracellular free Ca2+ concentration [( Ca2+]i) in skeletal muscle and that should have similar efficacy in treating and preventing the clinical manifestations of MH in response to a halothane/succinylcholine challenge. To test this hypothesis, experiments were carried out in four controls (Yorkshire) and eight MH-susceptible crossbreed swine (Poland China X Pietrain).

The effects of extracellular magnesium on myoplasmic [Ca2+] in malignant hyperthermia susceptible swine.

It is now well established that the pathophysiology of the malignant hyperthermia (MH) syndrome is related to a malfunction of intracellular calcium homeostasis. Magnesium plays important roles in the basic contractile properties of muscle, and many of its actions are antagonistic to those of calcium. The aim of this study was to determine the effectiveness of magnesium sulphate to prevent the MH episode in susceptible animals and correlate this with its effects on the intracellular free calcium [( Ca2+]i).

Azumolene reverses episodes of malignant hyperthermia in susceptible swine.

Azumolene is an analogue of dantrolene with much greater water solubility. Ten swine susceptible to malignant hyperthermia (MH) were triggered into MH episodes via the inhalation of halothane, and azumolene was effective in terminating all of the MH episodes. There was an inverse relationship between the dose of azumolene required to terminate the MH episode and the time it took for the pig to manifest the signs of MH.

Ketamine does not trigger malignant hyperthermia in susceptible swine.

The use of ketamine in individuals susceptible to malignant hyperthermia (MH) is controversial. We describe our experience with ketamine used for induction and/or maintenance of anesthesia in our herd of swine inbred for susceptibility to MH. A total of 76 MH-susceptible swine were given a total of 112 general anesthetics using ketamine as the induction drug.