title: The effects of morphine on isolated cutaneous canine vascular smooth muscle.
abstract: In order to evaluate the direct effects of morphine sulfate (MS) on vascular smooth muscle (VSM), a helical strip preparation of canine cutaneous VSM was prepared from vessels of approximately 150 to 250 mug internal diameter. When evaluated at a variety of muscle lengths from 20% to 60% above unstretched length, in the absence and in the presence of norepinephrine (2 to 10x10(-4) mg/cc), MS (10(-3) to 10(-1) mg/cc) failed to produce any noticeable effect. Thus, the well-known arteriolar dilator effect of MS is not a direct effect of the drug on VSM and it is not secondary to blockade of vascular alpha-adrenergic receptors.
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000187:drug effects*; D004285:Dogs; D004347:Drug Interactions; D066298:In Vitro Techniques; D009020:Morphine / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology
chemical_list: D009020:Morphine; D009638:Norepinephrine