Effect of noradrenaline on current- and voltage-clamped muscle cells of the guinea-pig vas deferens in normal Krebs solution.
The ionic mechanism underlying the time-dependent alteration in the action potential configuration by noradrenaline (NA) was studied using vas deferens muscles voltage-clamped according to the double sucrose gap method. Early exposure to NA enhanced the inward Ca2+ current (ICa) by increasing conductance whereas late exposure diminished ICa by reducing the driving force. The degree of increase in the peak outward K+ current (IK') was higher with a greater enhancement of ICa by NA but the late outward K+ current (IK) was insensitive to NA.
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First Department of Internal Medicine, Tohoku University School of Medicine, Japan.
Inomata
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D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004594:Electrophysiology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology*; D014649:Vas Deferens / Q000187:drug effects
D009638:Norepinephrine