Summary
Bay k 8644 is suggested to increase calcium influx through the voltage-dependent calcium channel. In isolated, blood-perfused sinoatrial node preparations of the dog, Bay k 8644 injected intra-arterially increased sinus rate as isoprenaline did. In isolated, blood-perfused papillary muscle preparations of the dog isoprenaline injected intra-arterially increased both the force of contraction of the papillary muscle and its spontaneous beating rate. In these preparations, however, Bay k 8644 failed to increase the beating rate, although it increased the force of contraction. These results are consistent with the concept that the slow inward current plays a role in sinoatrial nodal automaticity but not in automaticity of Purkinje fibres which was reflected as ventricular automaticity of the papillary muscle preparations used here.
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Satoh, K., Wada, Y. & Taira, N. Differential effects of Bay k 8644, a presumed calcium channel activator, on sinoatrial nodal and ventricular automaticity of the dog heart. Naunyn-Schmiedeberg's Arch. Pharmacol. 326, 190–192 (1984). https://doi.org/10.1007/BF00517319
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DOI: https://doi.org/10.1007/BF00517319