Immunoreactive bands were visualized using the enhanced chemiluminescence (ECL) plus or ECL prime systems and were quantified using densitometry. In addition, a portion of the RASMCs were further incubated for 24 h to detect cell viability using a 3-[4, 5-dimethylthiazol-2-phenyl]-2, 5-diphenyl-tetrazolium bromide (MTT) assay and cell death according to the Ponatinib concentration release of lactate dehydrogenase (LDH) into the medium. In some studies, RASMCs were pre-incubated with olmesartan, a JNK inhibitor (SP600125), and a p38 inhibitor
(SB203580) for 10 min, 20 min, and 4 h, respectively, before stimulation with cyclic mechanical stretch. Band intensities were quantified using the densitometry of the immunoblot with NIH Image J software. Olmesartan
(RNH-6270) was kindly provided by Daiichi-Sankyo Screening Library Co., Ltd. (Tokyo). All other materials were purchased from Wako (Kyoto) or Nakalai Tesque (Kyoto) unless stated otherwise. The antibodies used for western blot analysis, anti-pan- or phospho-SAPK/JNK (Thr183/Tyr185) antibody and anti-pan- or phospho-p38 MAP kinase (Thr180/Tyr182) antibody, were purchased from Cell Signaling Technology. The ECL plus and ECL prime systems were purchased from GE Healthcare. Collagen I was purchased from Nippon Meat Packers, Inc. (Osaka). All chemical compounds were dissolved in dimethyl sulfoxide (DMSO) to a final concentration of less than 1%, except where specifically noted. Data are reported as the mean ± standard deviation (S.D.). We used a Student’s t-test with Fisher’s post-hoc test for intergroup comparison. A P-value of <0.05 was considered to indicate statistical significance. The effect of cyclic mechanical stretch on RASMC death was examined by measuring the MTT reduction and LDH release from the cells. Fig. 1A and B show the viability and
death rate of RASMCs subject to cyclic mechanical stretch by 20% elongation for 0–4 h, respectively. It was observed that the cell viability was decreased by stretch in a time-dependent manner and 35% of cells were dead at 4 h, evaluated based on the MTT reduction (Fig. 1A). In accordance with these results, the LDH release from RASMCs was increased by stretch in a time-dependent manner up to 4 h (Fig. 1B). These results suggest that Dipeptidyl peptidase cyclic mechanical stretch-induced death in the RASMCs. Next, we examined the effect of olmesartan on cyclic mechanical stretch-induced death in RASMCs. As shown in Fig. 2, it was obvious that cell viability was significantly recovered with olmesartan treatment in a concentration-dependent manner. The effects of cyclic mechanical stretch on the activation of JNK and p38 were assessed using western blot analysis with phospho-specific antibodies. RASMCs were exposed to cyclic mechanical stretch with a 20% elongation for different periods of time and the phosphorylation of JNK and p38 was measured. As shown in Fig.