(A, B) Representative intravital fluorescence microscopic images (original magnification ×200) of regular perfused striated muscle capillaries after administration of saline (upper panel) and of GSR-induced perfusion failure of individual capillaries (arrows indicate non-perfused capillaries; lower panel). (C, D) Quantification of functional capillary density dependent on ZPI (C) or PZ (D) genotype. Data are given as box plots indicating the median with the 25th and 75th percentiles. Mann-Whitney rank-sum test, followed by Bonferroni correction; * p<0.05 vs. saline-treated mice within the same genetic background. Abbreviations: PZ, protein Z; ZPI, protein Z-dependent protease-inhibitor; GSR, generalized Shwartzman reaction. (GSR 4 hours: ZPI+/+ n=11, ZPI−/− n=14, PZ+/+ n=11, PZ−/− n=14; saline: ZPI+/+ n=11, ZPI−/− n=13, PZ+/+ n=12, PZ−/− n=12).