The effect of pH on tricaine methanesulfonate induced anaesthesia of the newt Notophthalmus viridescens

The anaesthetic tricaine methanesulfonate (TMS), when dissolved in distilled water, yields an acidic solution. To determine if pH affected the anaesthetic efficacy of TMS in the newt Notophthalmus viridescens, newts were anaesthetized in 0.1% TMS solutions adjusted to pH's of 3, 4, 5, 6, 7, or 8 with NaOH. As the pH increased, there was a significant decrease in the time required to induce anaesthesia and an increase in the time required to recover from the anaesthetic. We conclude that adjusting the pH of TMS solutions towards neutrality increases their anaesthetic efficacy.