Figure 9.

Simultaneous measurements of (A) phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1‐Thr⁸⁵⁵), of (B) phosphorylation of regulatory myosin light chain (MLC2‐Ser¹⁹) and of (C) tension in rat mesenteric arteries. Arterial segments were exposed to phenylephrine (Phe; 10 μM), cystamine (100 μM), KPSS (100 mM) or Y27632 (1 μM) alone or in combination. Once tension was measured, the preparations were snap‐frozen for immunoblotting for p‐MYPT‐ Thr⁸⁵⁵ and for MYPT. (B) Ratio of p‐MYPT1/MYPT1. Cystamine reduced the tension and basal phosphorylation of MYPT1 (p‐MYPT1/MYPT1), while phenylephrine‐induced increase in phosphorylation was unaltered. The ROCK inhibitor, Y27632 (1 μM), reduced both phenylephrine and basal p‐MYPT1/MYPT1. (C) Abscissae show wall tension and p‐MLC2‐Ser¹⁹/MLC2 ratio determined by Western blot in vessels mounted on wire myograph. Data are means ± SEM of vessel segments from 14 animals. *P < 0.05, ANOVA.