Abstract
The effects of the α1-agonist phenylephrine on the voltage-gated Ca2+-entry in vascular smooth muscle cells has been studied by measuring the agonist-induced changes of [Ca2+]i in K+-depolarized tissues. These changes have been estimated from the changes in fluorescence of the Ca2+-indicator fura-2, or have been assessed from the changes in 86Rb-efflux rate through Ca2+-activated K+-channels. Phenylephrine increases the force development in K+-depolarized tissues, but reduces [Ca2+]i and inhibits the 86Rb-efflux rate. However, in the presence of the Ca2+-entry blocker verapamil, phenylephrine increases both force development and [Ca2+]i. It is concluded that phenylephrine inhibits voltage-gated Ca2+-channels, and also induces an influx of calcium by activating a verapamil-insensitive pathway.
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Declerck, I., Himpens, B., Droogmans, G. et al. The α1-agonist phenylephrine inhibits voltage-gated Ca2+-channels in vascular smooth muscle cells of rabbit ear artery. Pflugers Arch. 417, 117–119 (1990). https://doi.org/10.1007/BF00370780
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DOI: https://doi.org/10.1007/BF00370780