Role of Protein Kinase C in the G Protein-Mediated Increase in Myofilament Ca2+ Sensitivity in Skinned Arterial Smooth Muscle of the Rabbit

Author(s):  
Takeo Itoh ◽  
Yoshimasa Watanabe ◽  
Makoto Yoshida ◽  
Akito Suzuki
1998 ◽  
Vol 274 (5) ◽  
pp. L842-L853 ◽  
Author(s):  
Larissa A. Shimoda ◽  
J. T. Sylvester ◽  
James S. K. Sham

Although endothelin (ET)-1 is an important regulator of pulmonary vascular tone, little is known about the mechanisms by which ET-1 causes contraction in this tissue. Using the whole cell patch-clamp technique in rat intrapulmonary arterial smooth muscle cells, we found that ET-1 and the voltage-dependent K+(KV)-channel antagonist 4-aminopyridine, but not the Ca2+-activated K+-channel antagonist charybdotoxin (ChTX), caused membrane depolarization. In the presence of 100 nM ChTX, ET-1 (10−10to 10−7 M) caused a concentration-dependent inhibition of K+ current (56.2 ± 3.8% at 10−7 M) and increased the rate of current inactivation. These effects of ET-1 on K+ current were markedly reduced by inhibitors of protein kinase C (staurosporine and GF 109203X) and phospholipase C (U-73122) or under Ca2+-free conditions and were mimicked by activators of protein kinase C (phorbol 12-myristate 13-actetate and 1,2-dioctanoyl- sn-glycerol). These data suggest that ET-1 modulated pulmonary vascular reactivity by depolarizing pulmonary arterial smooth muscle, due in part to the inhibition of KV current that occurred via activation of the phospholipase C-protein kinase C signal transduction pathway.


2000 ◽  
Vol 352 (2) ◽  
pp. 573 ◽  
Author(s):  
Lynn P. WEBER ◽  
Minoru SETO ◽  
Yasuharu SASAKI ◽  
Karl SWÄRD ◽  
Michael P. WALSH

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