[The comparative efficacy and differences in the molecular mechanism of the inotropic action of cardiac glycosides and nonglycoside cardiotropic agents on the contractile protein system of the myocardium].
The in vitro study on an isolated system of myocardial contractile proteins determined optimal concentrations of the positive inotropic action and biological activity ranges of beta-methyldigoxin (beta-MD), strophanthin K, K-strophantozide, beta-acetyldigoxin (beta-AD), milrinone, and amrinone. Optimal concentrations of the beta-MD and strophanthin K (10(-2) and 10(-6) M, respectively) significantly increased qualitatively and quantitatively the economy and thermodynamic efficiency, altered the energy transformation in the contractile protein system under the isometric contraction, whereas the beta-AD produced only the quantitative effect. However, the beta-MD and strophanthin K at concentrations exceeding the optimal one by one order lost the ability to produce the qualitative effect, retaining only the quantitative one in the actomyosin ensemble. The strophanthin K significantly increased the economy of a single actomyosin ensemble in the force generation phase and the beta-MD in the tension maintenance phase. Unlike the strophanthin K, the beta-MD did not slow down (did not worsen) the relaxation process. This provides grounds to conclude that the beta-MD produces most favorable effect on the energy transformation by myocardial contractile proteins.
Karsanov
N V
NV
Kipshidze
N N
NN
Sukoian
G V
GV
Guchua
Z I
ZI
Tatulashvili
D R
DR
Karsanov
V N
VN
Iarovaia
E V
EV
Magaldadze
V A
VA
Turmanauli
G S
GS
D000818:Animals; D002301:Cardiac Glycosides / Q000494:pharmacology*; D002316:Cardiotonic Agents / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects; D006321:Heart / Q000187:drug effects*; D066298:In Vitro Techniques; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism; D009124:Muscle Proteins / Q000187:drug effects* / Q000378:metabolism; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism; D011817:Rabbits
D002301:Cardiac Glycosides; D002316:Cardiotonic Agents; D009124:Muscle Proteins
Sravnitel'naia éffektivnost' i razlichiia v molekuliarnom mekhanizme inotropnogo deĭstviia nekotorykh serdechnykh glikozidov i neglikozidnykh kardiotropnykh sredstv na sistemu kontraktil'nykh belkov miokarda.