scholarly journals Electrical and mechanical effects of okadaic acid from black sponge on isolated guinea pig papillary muscles and rabbit sinus node cells.

1983 ◽  
Vol 33 ◽  
pp. 153
Author(s):  
Noriaki Kondo ◽  
Shoji Shibata ◽  
Yasumasa Tsukitani ◽  
Hiroyuki Kikuchi
Keyword(s):  
Guinea Pig ◽  
Okadaic Acid ◽  
Sinus Node ◽  
Papillary Muscles ◽  
Mechanical Effects

Electromechanical Effects of bPTH-(1-34) on Rabbit Sinus Node Cells and Guinea Pig Papillary Muscles

1988 ◽  
Vol 11 (5) ◽  
pp. 619-625 ◽  
Author(s):  
Noriaki Kondo ◽  
Shoji Shibata ◽  
Thomas E. Tenner ◽  
Peter K. Pang
Keyword(s):  
Guinea Pig ◽  
Sinus Node ◽  
Papillary Muscles ◽  
Electromechanical Effects

Evidence for physiological functions of protein phosphatases in the heart: evaluation with okadaic acid

1993 ◽  
Vol 265 (1) ◽  
pp. H257-H266 ◽  
Author(s):  
J. Neumann ◽  
P. Boknik ◽  
S. Herzig ◽  
W. Schmitz ◽  
H. Scholz ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Okadaic Acid ◽  
Guinea Pigs ◽  
Positive Inotropic Effect ◽  
Inotropic Effect ◽  
Papillary Muscles ◽  
Force Of Contraction ◽  
Phosphorylation State ◽  
Ventricular Cardiomyocytes ◽  
Channel Currents

Okadaic acid exerts a positive inotropic effect in cardiac preparations. We studied whether the positive inotropic effect of okadaic acid in cardiac preparations could be due to phosphatase inhibition and whether this inhibition affects the phosphorylation of cardiac proteins. In papillary muscles from guinea pigs, 30 microM okadaic acid increased force of contraction to 175% of predrug value. In isolated guinea pig ventricular cardiomyocytes, okadaic acid augmented single Ca(2+)-channel currents by enhancing channel availability. In homogenates from ventricles, 1 microM okadaic acid completely inhibited phosphorylase a phosphatase activity. In isolated 32P-labeled ventricular cardiomyocytes, 30 microM okadaic acid increased phosphorylation of phospholamban (PLB) and troponin inhibitor (TnI) to 325 and 284% of control, respectively. Furthermore, 30 microM okadaic acid increased phosphorylation of a hitherto unknown 23-kDa protein to 352% of control. It is concluded that the effects of okadaic acid could be mediated by increasing the phosphorylation state of several proteins including PLB, a 23-kDa protein, and TnI.

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