Key result
Phenylephrine stimulation of alpha 1-adrenoceptors in rat atrial heart muscle decreased K+ conductance, inducing depolarization and a TTX-sensitive Na+ window current.
Phenylephrine induces depolarization in rat atrial muscle by decreasing K+ conductance, which activates a TTX-sensitive Na+ window current and subsequently increases Ca2+ influx via Na+-Ca2+ exchange.
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Hypothesis-generating for alpha1 effects on atrial excitability; leaves open relevance to human arrhythmias.
Jahnel et al. (1991) studied Rat atrial heart muscle (experimental). Phenylephrine vs. Control conditions / phentolamine was evaluated on Transmembrane potential, currents and ion fluxes. Phenylephrine stimulation of alpha 1-adrenoceptors in rat atrial heart muscle decreased K+ conductance, inducing depolarization and a TTX-sensitive Na+ window current.
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