Concanavalin A- and fetal-calf-serum-induced rounding and myosin light chain phosphorylation in cultured smooth muscle cells
✍ Scribed by Yasuo Sasaki; Kunie Iwata; Yasuharu Sasaki
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 741 KB
- Volume
- 144
- Category
- Article
- ISSN
- 0021-9541
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✦ Synopsis
Chemical Industry, Co , Ltd , Asahr-mdchi 6-2700, Nobeokd 882, japan Rabbit aorta smooth muscle cells (SMC) in long-term culture retracted in less than 10 min in response to a sequential order of stimulations by concanavalin A [Con A) and fetal calf serum (FCS). With additional continuous stimulation by FCS, the SMC took on a circular shape and were anchored to the substrate by retraction fibrils. This rounding was observed only when the cells were sequentially stimulated by Con A and FCS. Depletion of intracellular Ca'+ stores by the addition of EGTA and Ca2+ ionophores inhibited the rounding. Transient phosphorylation of MLC,,, was observed in the initial stage during the SMC rounding. The extent of monophosphorylated MLC,, increased for up to 5 min to a maximal value of 49%. The diphosphorylated form reached a maximal value of 29% within 2 rnin; then both forms of MLC,, decreased. The process of the SMC rounding was inhibited by antimycin A or cytochalasins, in a dose-dependent manner, findings which suggested a dependency on both metabolic energy and actin-containing rnicrofilaments. The smooth-muscle-relaxing agent, HA1077, also inhibited the process of SMC rounding. These observations 5uggest that a cellular contractile process might be involved in rounding of SMC.
Methods
Cell cultures SMC were isolated from rabbit aorta and cultured in our laboratory . SMC were grown