Evaluation of the anesthetic effects of MS222 in the adult Mexican axolotl (Ambystoma mexicanum)

Figures & data

Figure 1 An axolotl in dorsal recumbency after a 20-minute immersion bath with MS222 (0.2%).

Notes: Note the increased erythema of the body surface and gill darkening. A complete loss of muscular tone and absence of the righting reflex following exposures with 0.2% and 0.4% MS222 was exhibited. Note also the position of the oximetry probe at mid-thorax (held in place with a loosely fitted elastic) used to evaluate the heart rate and the blood oxygen saturation.

Figure 2 Percentage of adult axolotls (n=9; six females and three males) reacting to the acetic acid test and withdrawal reflex following a 20-minute 0.2% MS222 immersion bath.

Notes: −15 minutes, baseline values prior to immersion bath; time zero, time at which animals were removed from the immersion bath.

Figure 3 Heart rate (beats/min) and blood oxygen saturation (%) (mean ± standard deviation) of adult axolotls (n=9; six females and three males) following a 20-minute 0.2% MS222 immersion bath.

Notes: A priori comparisons to baseline showed significant differences at 0, 15, and 30 minutes for heart rates, and at 45 minutes and 60 minutes for blood oxygen saturation (*P<0.01, **P>0.05). All a priori contrasts during anesthesia up to recovery were nonsignificant for both parameters. −15 minutes, baseline values prior to immersion bath; time zero, time at which animals were removed from the immersion bath.

Figure 4 Cloacal and superficial temperatures (°C) (mean ± standard deviation) results of adult axolotls (n=9; six females and three males) following a 20-minute 0.2% MS222 immersion bath.

Notes: All a priori contrasts to baseline were significant for both body surface (P<0.0001) and cloacal (P<0.01) temperatures. A priori contrasts during anesthesia up to recovery were nonsignificant. Note that tank water temperature before the MS222 immersion bath was 18°C. MS222 solution was kept at room temperature (21°C). −15 minutes, baseline values prior to immersion bath; time zero, time at which animals were removed from the immersion bath.

Figure 5 Heart rate (beats/min) and blood oxygen saturation (%) (mean ± standard deviation) of adult axolotls (n=3 females) following a 20-minute 0.4% MS222 immersion bath.

Notes: −15 minutes, baseline values prior to immersion bath; time zero, time at which animals were removed from the immersion bath.

Figure 6 Cloacal and superficial temperatures (°C) results of adult axolotls (n=3 females) following a 20-minute 0.4% MS222 immersion bath.

Notes: Note that tank water temperature before the MS222 bath immersion was 18°C; MS222 solution was kept at room temperature (21°C). −15 minutes, baseline values prior to immersion bath; time zero, time at which animals were removed from the immersion bath.