Pharmacological properties of alpha 1-adrenoceptor-mediated vasoconstrictions in dog and monkey lingual arteries: evidence for subtypes of alpha 1-adrenoceptors

Heart Vessels. 1992;7(2):82-90. doi: 10.1007/BF01744453.

Abstract

We examined whether alpha 1-adrenoceptor-mediated vasoconstrictions were due to extra- or intracellular Ca2+ movements, and whether they were subdivided into alpha 1-adrenoceptor subtypes in dog and monkey lingual arteries. The NE-induced vasoconstriction in dog lingual arteries was mostly dependent on Ca2+ influx from the extracellular space, since it was readily blocked by a Ca2+ entry blocker, diltiazem, and the NE-induced response was attenuated approximately 90% in Ca(2+)-free solution. On the other hand, in monkey lingual arteries, diltiazem failed to depress the NE-induced dose-response curve, and the response was attenuated only about 60% in Ca(2+)-free solution. The vasoconstrictor response to 10mg caffeine in normal KHS was almost the same as that to 1 micrograms NE in Ca(2+)-free solution in both kinds of arteries, suggesting that alpha 1-adrenoceptor-mediating vasoconstrictions require a different number of sources of Ca2+ in different blood vessels. Pretreatment of preparations with CEC (an alpha 1B-antagonist) significantly suppressed and shifted the dose-response curve for NE to the right in monkey lingual arteries, but it had no significant effect in dog lingual arteries. However, WB4101 (an alpha 1A-antagonist) showed almost the same potency in blocking vasoconstrictor responses as bunazosin in both kinds of arteries (the pA2 values were not significantly different). Moreover, responses to ME (an alpha 1A-agonist) were blocked by diltiazem as well as by bunazosin and WB4101, while CEC had no blocking effect on ME-induced responses.(ABSTRACT TRUNCATED AT 250 WORDS)

MeSH terms

  • Adrenergic alpha-Antagonists
  • Animals
  • Calcium / metabolism*
  • Calcium Channels / drug effects*
  • Clonidine / analogs & derivatives
  • Clonidine / pharmacology
  • Diltiazem / pharmacology*
  • Dioxanes / pharmacology
  • Dogs
  • Dose-Response Relationship, Drug
  • Macaca
  • Muscle, Smooth, Vascular / drug effects*
  • Norepinephrine / pharmacology*
  • Receptors, Adrenergic / classification
  • Receptors, Adrenergic / drug effects*
  • Signal Transduction / drug effects
  • Species Specificity
  • Tongue / blood supply*
  • Vasoconstriction / drug effects*

Substances

  • Adrenergic alpha-Antagonists
  • Calcium Channels
  • Dioxanes
  • Receptors, Adrenergic
  • chlorethylclonidine
  • (2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane
  • Diltiazem
  • Clonidine
  • Calcium
  • Norepinephrine