The positive inotropic dihydropyridine Bay K 8644 does not affect calcium sensitivity or calcium release of skinned cardiac fibres.
BAY K 8644 is a positive inotropic dihydropyridine which concentration-dependently increased contractile force in guinea-pig atria at 10 to 1000 nmol/l. In chemically skinned cardiac fibres from guinea-pig hearts the substance did not change the tension induced by calcium. Also BAY K 8644 did not release calcium from intracellular myocardial stores like caffeine since it failed to evoke a contractile response in saponin-treated, calcium-loaded cardiac muscle. Thus, the drug exerts its effects neither by sensitizing the contractile apparatus to calcium nor by a caffeine-like action.
Thomas
G
G
Gross
R
R
Pfitzer
G
G
Rüegg
J C
JC
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D009543:Nifedipine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013268:Stimulation, Chemical
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009543:Nifedipine; D002118:Calcium