Effects of ketamine on NOS mRNA expression in pulmonary tissues from ovalbumin-sensitized and -challenged rats. (A) Expression of NOS mRNA in pulmonary tissues was detected by RT-PCR. Representative RT-PCR products for nNOS, iNOS, eNOS and β-actin (internal control) are shown. The groups are as shown in Figure 1. Lane 1, PBS; lane 2, OVA; lane 3, 12.5 mg/ml; lane 4, 25 mg/ml; lane 5, 50 mg/ml; lane 6, 50 μg/kg; lane 7, 100 μg/kg. (B) Semiquantitative densitometry was used to analyze iNOS and eNOS mRNA expression levels, normalized to that of β-actin. Bars represent mean ± SEM expressed as the relative density of NOS versus that of β-actin (n = 6–8/group). # P < 0.05 vs. PBS control; * P < 0.05 vs. OVA control.