Fig. 2.

The mast cell protease-deficient mouse lines Mcpt4^-/-Mcpt6^-/-Cpa3^-/-, Cpa3^Y356L,E378A, and Mcpt6^-/- scratch more than wild-type controls when injected with ET-1. a When injected with ET-1 (20 pmol), Mcpt4^-/-Mcpt6^-/-Cpa3^-/- mice (n = 14) had a much higher number of scratching episodes in 60 min than wild-type controls (WT, n = 12). b Mcpt4^-/-Mcpt6^-/-Cpa3^-/- mice spent more total time scratching during the 60 min test. c The Mcpt4^-/-Mcpt6^-/-Cpa3^-/- mice also had shorter scratching episodes on average than controls. d The results from (a) analyzed over time. The Mcpt4^-/-Mcpt6^-/-Cpa3^-/- mice scratched more frequently than controls overall (vertical significance bar), and post hoc analysis showed that they scratched significantly more in the first four intervals of the test. e Both Mcpt6^-/- (n = 8) and Cpa3^Y356L,E378A mice (Cpa3^Y3, n = 8) scratched more frequently in 60 min than wild-type controls (n = 11) when injected with ET-1. Mcpt4^-/- mice (n = 7) did not differ from controls in their scratching behavior. fMcpt6^-/- and Cpa3^Y356L,E378A mice also spent more time scratching after ET-1 injection than controls. g But no difference was seen in the mean length of scratching episodes. h The results from (e) analyzed over time. Both Mcpt6^-/- and Cpa3^Y356L,E378A mice scratched more than controls over the duration of the test (indicated by vertical significance bar). Further analysis showed that Cpa3^Y356L,E378A mice scratched more than controls in the intervals between 10 and 40 min (indicated by stars), and Mcpt6^-/- mice scratched significantly more between 10 and 30 min (indicated by #). Results are presented as mean ± SEM. #/*P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; ****P ≤ 0.0001; n.s, not significant; Student’s t test (a-c); 2-way ANOVA with Bonferroni multiple comparison (d, h);

1-way ANOVA (e-g). Statistical outliers as identified by Grubb’s test are indicated with the symbol §