[Effects of magnesium and calcium on muscle contractility and neuromuscular blockade produced by muscle relaxants and aminoglycoside].
The muscle contractility and neuromuscular blockade of muscle relaxants are influenced by the electrolytes, especially magnesium ion(Mg2+) and calcium ion(Ca2+), in the extracellular fluid. The present study was designed to evaluate the effects of Mg2+ and Ca2+ on muscle contractility and on the blocking properties of d-tubocurarine, succinylcholine and aminoglycoside antibiotics, tobramycin in vitro, using rats' phrenic nerve-hemidiaphragm preparations. Mg2+ inhibited the twitch tensions in a concentration dependent manner. A low concentration of Ca2+ decreased the twitch tensions, but a high concentration of Ca2+ had no effect on them. Mg2+ potentiated the block produced by d-tubocurarine, succinylcholine and tobramycin depending on the concentration of Mg2+, and good regression lines were obtained. Ca2+, however, antagonized the neuromuscular blockade of the three drugs at any level of Mg2+ concentration. From these findings, it should be noticed that special care must be taken to prevent a profound neuromuscular blockade due to the drug interaction of each drug when a muscle relaxant or an aminoglycoside antibiotics is administered to a patient suffering from hypermagnesemia and/or hypocalcemia.
Okamoto
T
T
Department of Anesthesiology, National Defense Medical College, Saitama.
D000617:Aminoglycosides / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology*; D009469:Neuromuscular Junction / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000617:Aminoglycosides; D009466:Neuromuscular Blocking Agents; D008274:Magnesium; D002118:Calcium