• 동의생리병리학회지
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• 제17권5호
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• pp.1335-1338
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• 2003

We have previously reported that the vasodilatory effect of BanhabackchuIChunma-tang(半夏白朮天麻湯; BCT), a herbal formula, and its mechanism might be associated with at least in part NO pathway. In the present study, we studied the influence of BanhabackchulChenuma-tang (BCT) on the phosphorylation of LC20, in parallel, the distribution of α-protein kinase C(PKCα) by phenylephrine was monitored using laser scan confocal immunofluorescent microscopy in freshly isolated ferret portal vein smooth muscle living single cells. Phenylephrine stimulation induced LC20 phosphorylation and translocation of PKCα. However, BCT dephosphorylated LC20 phosphorylation and inhibited the translocation of PKCα. Our results demonstrate that the mechanism of relaxant effect of BanhabackchulChunma-tang inhibition is associated with inhibition of PKCα activation and LC20 phosphorylation.

• 동의생리병리학회지
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• 제17권2호
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• pp.461-466
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• 2003

The primary mechanism of smooth muscle contraction is phosphorylation of the 20 kDa myosin light chains(LC20) by a myosin light chain kinase(MLCK). Relaxation, then, is generally the result of dephosphorylation of LC20 by myosin phosphatase(MP). Changes in MP activity is one of the important mechanisms in the regulation of Ca2+-sensitivity. Inhibition of MP activity is linked to an increase in phosphorylated myosin light chain(MLC) without an increase in [Ca/sup 2+/]i-levels. It is now generally accepted that Rho-kinase phosphorylates 130 kDa regulatory and myosin binding subunits(M130, MYPT) of MP, which results in an inhibition of MP activity. In addition Rho-kinase can also directly phosphorylate MLC. In the present study, LC20 phosphorylation and MP subunits translocation to the cell membrane were investigated in freshly isolated ferret portal vein smooth muscle single cells treated with PGF2α. We also examined the effect of Y27632(10-5mol/L), Rho-kinase inhibitor, in the MP subunits localization to compare with butanol fraction of Fructus Crataegi in its effect. Butanol fraction of Fructus Crataegi(BFFC; 1㎎/㎖) was more effective in PGF2α induced contraction than those of phenylephrine in its vasodilation effect. It significantly(P<0.05) dephosphorylated the LC20 at time indicated. In addition, the dissociation of subunits are inhibited by BFCF treatment. The results indicate that, in the smooth muscle cells, the relaxation effect of BFFC is associated with increase of MP activity based on inhibition of dissociation of the catalytic and targeting subunits of the phosphatase, and thus decrease the sensitivity of LC20 phosphorylation for Ca/sup 2+/.