title: Calcium pools for noradrenaline and potassium-induced contractions of rat portal vein.
abstract: The contractile responses of isolated normal and Ca-depleted rat portal veins to varying concentrations of noradrenaline (NA) and K+ have been studied with a view to further clarifying the sources of Ca for contraction using both agents. The comparably rapid times-to-peak of NA and K+ contractions of normal (Ca-containing) strips suggest mobilization of a common Ca pool, perhaps superficial: whereas, following Ca-depletion. NA appears to mobilize a superficial pool more readily than K+. Following K+ depolarization in Ca-free medium, NA produced a contraction sensitive to ryanodine, suggesting Ca release from an intracellular pool.
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000494:pharmacology*; D011169:Portal Vein / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012433:Ryanodine / Q000494:pharmacology; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D012433:Ryanodine; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine