The caffeine contracture test for malignant hyperthermia: caffeine citrate, caffeine benzoate or caffeine free base?
The aim of the present study was to investigate whether the three different caffeine preparations--caffeine citrate, caffeine benzoate and the free base--used for in vitro diagnosis of malignant hyperthermia susceptibility--produced the same amount of contracture in rat diaphragm. At equimolar caffeine concentrations, the pure base generated more tension in the rat diaphragm muscle than caffeine benzoate or caffeine citrate. The citrate lowers the pH and the free Ca2+ concentration of the test bath and thus suppresses the caffeine contracture. The benzoate is believed to inhibit the caffeine contracture by its carbonyl group in a way similar to the effect of benzocaine.
Heytens
L
L
Department of Intensive Care, University Hospital Antwerp, Belgium.
Heffron
J J
JJ
Camu
F
F
D000818:Animals; D001565:Benzoates; D002110:Caffeine; D002951:Citrates; D004198:Disease Susceptibility; D004338:Drug Combinations; D008297:Male; D008305:Malignant Hyperthermia / Q000175:diagnosis*; D009119:Muscle Contraction / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains
D001565:Benzoates; D002951:Citrates; D004338:Drug Combinations; D002110:Caffeine; C025741:caffeine, sodium benzoate drug combination; C026189:caffeine citrate