1. Morphine tolerance increases [3H]MK-801 binding affinity and constitutive neuronal nitric oxide synthase expression in rat spinal cord 
Chih-Shung Wong, Ming-Man Hsu, Yen-Yen Chou, Pao-Luh Tao, Che-Se Tung 
British Journal of Anaesthesia 
Volume 85, Issue 4, Pages (October 2000)
DOI: /bja/
Copyright © 2000 British Journal of Anaesthesia Terms and Conditions

2. Fig 1
The effects of MK-801 on the development of morphine tolerance. Morphine tolerance (MO) was induced by continuous infusion (10 μg h−1 i.t.) for 5 days. The effect of MK-801 on morphine tolerance was examined by co-administering MK μg h−1 i.t. (MO+MK) with morphine for 5 days. The antinociceptive effect of continuous MK μg h−1 i.t. infusion (MK) was also examined. The control group was infused with the same amount of normal saline. Tail-flick latencies were measured daily for 5 days. All data points are averages of results from ≥10 rats, and the results are expressed as means±sem. *P<0.05, **P<0.01, ***P<0.001 compared with the morphine-infused group.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2000 British Journal of Anaesthesia Terms and Conditions

3. Fig 2
Scatchard analysis of [3H]MK-801 binding in rat spinal cord membranes with various i.t. drug infusions. Rats were continuously infused with saline (control), morphine 10 μg h−1 (MO), MK μg h−1 (MK) or a combination of morphine and MK μg h−1 (MO+MK) for 5 days. Rats were killed and their spinal cords removed on the sixth day. Membranes were prepared for [3H]MK-801 binding assays. [3H]MK-801 (0.1–60 nM) was used as the radiolabelled ligand in the presence of glycine (10 μM) and NMDA (100 μM). Unlabelled MK-801 (10 μM) was used to determine nonspecific binding. Data points are from one of the six experiments, each with three-pooled lumbosacral segments of spinal cords and performed in triplicate.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2000 British Journal of Anaesthesia Terms and Conditions

4. Fig 3
nNOS protein expression in the dorsal lumbosacral segments of rat spinal cords after various drug treatments, measured by western blot analysis. Rat spinal cords were obtained and treated as in Fig. 1. The dorsal lumbosacral segments of rat spinal cords were used for western blot analysis as described in Materials and methods. The 155 kDa nNOS protein band revealed by monoclonal nNOS antibody on a typical western blot are shown at the top. The positive control of nNOS (+nNOS; 1 μg) is shown in the right-most lane. The optical density of each protein band was quantified by densitometry and the relative optical density was calculated by taking the density of the control band as 100%. The mean intensity of the nNOS protein bands in the four groups is shown below. Data are expressed as mean±sem of results from 10 rats in each group. **P<0.01 (control group compared with MO group), *P<0.05 (MO group compared with MO+MK group). C, Control (normal saline); MO, morphine; MK, MK-801; MO+MK, morphine co-administered with MK-801.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2000 British Journal of Anaesthesia Terms and Conditions