TABLE 1

Effect of drug treatments on minute volume in mice breathing 5% CO2 in air

All values are mean ± S.E.M. of 5-minute averages. The predrug baseline values are taken from the 5-minute time bin just preceding the drug injection. Postdrug values are taken from the 15- to 20-minute time bin after the injection.

Drug TreatmentPredrug Baseline15 Minutes Postdrugn
Minute Volume (ml/min)Minute Volume (ml/min)
Saline157.3 ± 19.0144.7 ± 13.36
Morphinea229.3 ± 8.8137.8 ± 9.9*6
Morphineb148.4 ± 7.890.5 ± 8.5*7
Morphinec156.4 ± 4.587.6 ± 5.6*7
Tamoxifen152.6 ± 25.1144.2 ± 26.86
Mor pellet—day 6160.5 ± 6.8148.1 ± 9.76
+ morphine
Mor pellet—day 6141.8 ± 9.7140.8 ± 11.76
+ tamoxifen
Mor pellet—day 6154.2 ± 12.396.8 ± 10.0*6
+ tamoxifen
+ morphine
Mor pump—day 6134.2 ± 11.8132.3 ± 6.47
+ morphine
Mor pump—day 6147.2 ± 4.799.0 ± 3.6*7
+ tamoxifen
+ morphine
Meth pump—day 6158.8 ± 7.3147.7 ± 14.17
+ morphine
Meth pump—day 6143.7 ± 12.8130.8 ± 5.97
+ tamoxifen
+ morphine
Bup pump—day 6161.0 ± 10.7158.7 ± 13.57
+ morphine
Bup pump—day 6158.9 ± 14.1162.1 ± 12.27
+ tamoxifen
+ morphine
Calphostin C142.5 ± 18.1145.1 ± 9.87
SP600125158.9 ± 9.6163.4 ± 11.87

  • Bup, buprenorphine; Meth, Methadone; Mor, morphine.

  • a,b,c Indicate data for the respiratory-depressant effect of morphine in naive mice that were performed on three separate occasions—at the same time as the experiments to study amorphine pellet,/methadone pump/buprenorphine pump, bmorphine pump, and ccalphostin C/SP600125. Unless otherwise stated, there was no significant change from predrug baseline levels. Values were compared using a paired two-way Student’s t test.

  • ↵* Indicates a significant change (P < 0.05) from predrug baseline values.