Figure 6. The time-of-day variation of Rock2 mRNA expression and ROCK2 kinase activity is regulated by BMAL1 and is involved in the time-of-day variation of smooth-muscle contraction.

(A) Real-time PCR analysis of Rock2 mRNA expression in mesenteric arteries (n = 3–5). (B and C) Representative Western blots (B) and quantitative data (C; n = 7–8) of total MYPT1 (T-MYPT1) and phosphorylated MYPT1 at Thr853 (p-MYPT1⁸⁵³) in mesenteric arteries. (D) Concentration-response curve showing that the time-of-day variation in vasoconstriction induced by 5-HT was diminished by pretreatment of mesenteric arteries with Rho-kinase inhibitor Y27632 (10 μM, 30 min; n = 7–8). Veh, vehicle (DMSO). *P < 0.05 vs. ZT17 + vehicle at 10 μM 5-HT.