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 cardic muscle. Thus, the drug exerts its effects neither by sensitizing the contractile apparatus to calcium nor by a caffeine-like action.
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Thomas, G., Groß, R., Pfitzer, G. et al. The positive inotropic dihydropyridine BAY K 8644 does not affect calium sensitivity or calcium release of skinned cardiac fibres. Naunyn-Schmiedeberg's Arch. Pharmacol. 328, 378–381 (1985). https://doi.org/10.1007/BF00692904
- Skinned cardiac fibres
- Positive inotropic
- Calcium release
- BAY K 8644