F. Ledda, P. Marchetti, A. Manni
Sep 1, 1971
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Influential Citations
33
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Quality indicators
Journal
Pharmacological Research Communications
Abstract
Abstract Studies have been carried out on the effect of phenylephrine hydrochloride, at various concentrations (2×10 −6 , 5×10 −6 , 1×10 −5 g/ml), on transmembrane action potentials and effective refractory period in the Purkinje fibres of sheep heart. The amine, at all three concentrations, increased the duration of the action potential and effective refractory period in electrically driven preparations. When applied at the higher concentration, phenylephrine induced a positive chronotropic effect in spontaneously beating preparations; this effect was associated with an increased steepness of the pacemaker potential. The results may be interpreted according to the point of view that myocardial alpha receptors contribute to the modulation of the repolarization phases of the action potential.