Melatonin mediates two distinct responses in vascular smooth muscle

Eur J Pharmacol. 1998 Mar 12;345(1):67-9. doi: 10.1016/s0014-2999(98)00064-8.


The pineal hormone melatonin was found to produce two distinct contractile responses in vascular smooth muscle. In isolated rat caudal artery segments, denuded of endothelium, melatonin (10(-10)-10(-7) M) potentiated phenylephrine-induced contractions in a concentration-dependent manner. At higher melatonin concentrations (10(-7)-10(-5) M), however, the potentiating effect was attenuated. In the presence of the melatonin MT2 receptor antagonist, 4-phenyl-2-acetamidotetraline (4P-ADOT), the attenuated constrictor responses were selectively enhanced. These results are consistent with the hypothesis that melatonin activates two receptor subtypes in vascular smooth muscle; MT2 receptors may induce relaxation, while a second receptor subtype mediates vasoconstriction.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adrenergic alpha-Agonists / pharmacology
  • Animals
  • Drug Synergism
  • In Vitro Techniques
  • Male
  • Melatonin / pharmacology*
  • Muscle Contraction / drug effects
  • Muscle Relaxation / drug effects
  • Muscle, Smooth, Vascular / drug effects*
  • Phenylephrine / pharmacology
  • Rats
  • Rats, Inbred F344
  • Receptors, Cell Surface / antagonists & inhibitors
  • Receptors, Cell Surface / metabolism
  • Receptors, Cytoplasmic and Nuclear / antagonists & inhibitors
  • Receptors, Cytoplasmic and Nuclear / metabolism
  • Receptors, Melatonin
  • Tetrahydronaphthalenes / pharmacology
  • Vasoconstriction / drug effects


  • 4-phenyl-2-acetamidotetralin
  • Adrenergic alpha-Agonists
  • Receptors, Cell Surface
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Melatonin
  • Tetrahydronaphthalenes
  • Phenylephrine
  • Melatonin