Effect of synthetic vasopressins on the myocardial contractile force in the isolated guinea-pig atria

1965 ◽  
Vol 21 (8) ◽  
pp. 474-475 ◽  
Author(s):  
J. Nakano ◽  
J. S. Shackford
Keyword(s):  
Guinea Pig ◽  
Contractile Force ◽  
Myocardial Contractile Force ◽  
Myocardial Contractile ◽  
Guinea Pig Atria

Correlation between myocardial contractile force and cytosolic inorganic phosphate during early ischemia

1997 ◽  
Vol 272 (3) ◽  
pp. H1333-H1341 ◽  
Author(s):  
M. X. He ◽  
S. Wang ◽  
H. F. Downey
Keyword(s):  
Inorganic Phosphate ◽  
Contractile Force ◽  
Left Ventricular ◽  
Resonance Spectroscopy ◽  
Rat Hearts ◽  
Initial Control ◽  
Myocardial Contractile Force ◽  
Myocardial Contractile ◽  
Developed Pressure

To test the role of inorganic phosphate (Pi) in downregulation of myocardial contractile force at the onset of ischemia, Pi of rat hearts was determined with 31P nuclear magnetic resonance spectroscopy. Forty cycles of brief hypoperfusion (30% of baseline flow for 33 s) were used to achieve a time resolution of 0.512 s for comparing dynamic changes in Pi and contractile force. Initial control values of left ventricular developed pressure (LVP), heart rate, and oxygen consumption were 136 +/- 11 mmHg, 236 +/- 4 beats/min, and 95 +/- 3 microl O2 x min(-1) x g(-1); these values were unchanged at the end of the experiment. During the first 10 s of hypoperfusion, Pi increased at a rate (percentage of the total observed change) faster than the decrease in LVP; Pi and LVP then changed at the same rate during the remainder of the hypoperfusion. ADP did not change in advance of LVP. Intracellular pH did not change. The results indicate that Pi plays an important role in initiating the downregulation of myocardial contractile force at the onset of ischemia. Perfusion pressure also declined faster than LVP at the onset of ischemia, indicating potential importance of vascular collapse in contractile downregulation during early ischemia.

The increase in calcium binding of cardiac plasma membrane lipoprotein caused by general anesthetics and alcohol

1980 ◽  
Vol 58 (5) ◽  
pp. 525-530 ◽  
Author(s):  
S. Tsuyoshi Ohnishi ◽  
David M. Obzansky ◽  
Henry L. Price
Keyword(s):  
Plasma Membrane ◽  
Calcium Binding ◽  
Contractile Force ◽  
General Anesthetics ◽  
Myocardial Depression ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Myocardial Contractile Force ◽  
Myocardial Contractile ◽  
Membrane Lipoprotein

(1) Ca2+-binding lipoprotein was purified from dog heart plasma membrane and the effect of several general anesthetics, ethanol, and acetaldehyde on the Ca2+ binding was studied.(2) These drugs, which are known to cause myocardial depression increased the Ca2+ binding at clinically useful concentrations.(3) These results raise the possibility that these drugs, by increasing the Ca2+ binding to the plasma membrane, limit the availability of superficially located Ca2+ for excitation–contraction coupling and result in depression of myocardial contractile force.

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