Figure 5. Age-dependent changes in R-R interval and M2 muscarinic receptor and AchE gene expression in peripheral mononuclear white blood cells from normal (N) and vagal hyperreactive (H) rabbits.
(a) M2 muscarinic receptor and AchE gene expression were assessed in peripheral mononuclear white blood cells by quantitative RT-PCR and normalized to the rabbit 18S housekeeping gene. Values show amplification ratio calculated according to the 2−ΔΔCt method of 8–9 (N) and 7–11 (H) experiments. *: P = 0.0262 and **: P = 0.0122 versus 5 weeks-old rabbits within the N and the H group, respectively. (b) R-R intervals were measured in conscious rabbits challenged with PNE 500 µg kg−1 following the procedure described in Material and Methods. Values are means ± SD of 11 N and 15 H rabbits. *: P = 0.0179 and **: P = 0.0110 versus 7 weeks-old rabbits within the H group.