Inhibitory alpha-adrenergic action of phenylephrine in guinea pig taenia caecum.
Phenylephrine, a selective alpha-adrenergic stimulant, caused a maximal relaxation of the taenia from guinea pig caecum in the concentration of 10(-6) g/ml. Phenylephrine in this concentration did not influence intracellular cyclic AMP and cyclic GMP levels. Although phenylephrine abolished the spontaneous spike discharge, no change was detected in 45Ca-uptake and 45Ca-efflux on the tissue level after phenylephrine. Ca-uptake and Ca-release on the subcellular level were also not influenced by phenylephrine. In Ca free-solution phenylephrine inhibited the response to CaCl2. Phenylephrine increased 42K-efflux in the normally polarized taenia and also in the K-depolarized taenia.
D000200:Action Potentials / Q000187:drug effects; D000316:Adrenergic alpha-Agonists; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D002432:Cecum / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D009712:Nucleotides, Cyclic / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D009712:Nucleotides, Cyclic; D010656:Phenylephrine; D011188:Potassium; D002118:Calcium