Figure 1.
MT depolymerization enhances myocyte contractility. (A) Normalized calcium transient (F/Fo) for control (black) and colchicine-treated (purple) cells. (B) Peak calcium, time to peak, and decay time determined from individual traces (N = 6 hearts, n = 43 dimethylsiloxane vehicle (DMSO) cells, n = 48 colchicine-treated cells). (C) Relative shortening (change in SL divided by resting SL) with time. (D) Peak shortening, shortening, and relaxation times from individual traces from identical cells analyzed in (B). (E) The average shortening velocity for DMSO- and colchicine-treated RCMs from (A) and (C). (F) Peak shortening and relaxation velocity determined for individual data points. Statistical significance was determined as *p<0.05, ∗∗p < 0.01 or ***p <0.001 compared to DMSO, Student’s t-test. (G) A comparison of changes in contractile velocities and fractional shortening upon various manipulations to depolymerize MTs or alter MT-dTyr. Each treatment condition is displayed normalized to its relative control (for example, DMSO treated for PTL or a null-encoding adenovirus (AdV-Null) for AdV-TTL). Colchicine data are from the current study. PTL and taxol data are replotted from (16). TTL overexpression and knock-down data are replotted from (2). Data in (Β), (D), (F), and (G) are means with standard error bars. To see this figure in color, go online.