2a). Compared Rucaparib Sigma to normal animals, M2 mRNA relative quantities were increased in all rabbits displaying baroreflex dysfunction and vagal hyperreactivity (Fig. 2b). Figure 2 M2 muscarinic receptor gene expression in peripheral mononuclear white blood cells from normal (N) and vagal hyperreactive (H) rabbits. AchE gene expression and enzyme activity In an attempt to better characterise vagal disorders in H rabbits, we looked at whether AchE gene expression and enzyme activity were also changed in these animals. Vagal hyperreactive rabbits displayed an AchE mRNA amplification ratio of 3.6 versus normal rabbits (Fig. 3a,b); this was associated with twice the enzyme activity in erythrocytes (Fig. 3c).

When AchE was blocked by intravenous administration of neostigmine, a specific AchE inhibitor, H rabbits displayed massively increased bradycardia following PNE injection (up to 10-fold higher in some individuals; Fig. 4). These data confirmed that AchE enzyme activity was increased in the hearts of these animals. Taken together, the findings showed up-regulation of AchE in H rabbits. Figure 3 AchE cardiac gene expression and enzyme activity in erythrocytes from normal (N) and vagal hyperreactive (H) rabbits. Figure 4 Effect of AchE enzyme blockade in normal (N) and vagal hyperreactive (H) rabbits. Evolution of vagal disorders with age As a next step, age-dependent changes in vagal disorders and their functional consequences on R-R intervals were assessed in normal and hyperreactive rabbits. Blood samples were collected at the ages of 5 and 7 weeks.

The M2 expression decreased between the 5th and the 7th week of age in rabbits with normal vagal responses, whereas it remained unchanged in hyperreactive animals (Fig. 5a). In contrast, the AchE expression remained stable in N rabbits but increased significantly in H rabbits within the same period (Fig. 5a). Consequently, the M2/AchE ratio was similar whatever the age and the strain (Fig. 5a). 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. Functionnal disorders appeared after 7 weeks of age: R-R interval duration was similar in all rabbits up to 7 weeks and then increased in H rabbits, while remaining stable in N animals (Fig. 5b).

Despite SD error-bars appear overlapping on this figure, data were significantly different (P=0.0179 at 8�C11 weeks and P=0.011 at 12�C14 weeks compared to values observed at 7 weeks). Mortality study Mortality has been assessed in Anacetrapib a population of 2150 normoreactive rabbits and 385 hyperreactive animals. In hyperreactive animals, the altered changes in M2 muscarinic receptor and AchE expression were associated with an abnormally high mortality rate between 5 to 7 weeks of age: 52% in H rabbits versus 13% in normal rabbits. Mortality was higher in male than female (57% versus 43%).