Contraction of major artery segments of rat by fish neuropeptide urotensin II

Am J Physiol. 1987 Feb;252(2 Pt 2):R361-6. doi: 10.1152/ajpregu.1987.252.2.R361.


Urotensin II (U II) caused marked concentration-dependent contractions of helical strips from several major arteries of the rat. The thoracic aorta was most sensitive; the apparent concentration of U II producing half-maximal contraction was 6.8 X 10(-10) M. Papaverine, dibutyryl cyclic AMP, forskolin, and nitroprusside antagonized the contractile responses to U II at the apparent concentrations producing 50% inhibition (IC50) of 7.6 X 10(-6), 2.1 X 10(-4), 2.5 X 10(-6), and 1.5 X 10(-8) M, respectively. Verapamil, a calcium channel-blocking agent, partially inhibited the contractile response to U II at IC50 = 6.5 X 10(-6) M. Maximal relaxation, i.e., a complete inhibition, could not be obtained even at a concentration of 3 X 10(-5) M verapamil. Cyproheptadine reduced the U II-induced contraction at higher concentrations. Phentolamine (10(-5) M), propranolol (10(-5) M), atropine (10(-4) M), tetrodotoxin (10(-6) M), burimamide (10(-5) M), and indomethacin (10(-5) M) did not change the U II-induced contraction. At higher concentration, U II (10(-8) M) induced a small contraction of aortic strips in Ca2+-free Krebs Henseleit solution similar to that of norepinephrine, but the U II-induced contraction was not inhibited by phentolamine or propranolol. The action of U II did not require the presence of endothelial cells. It is concluded that U II acts on vascular smooth muscle and induces the contraction partly through intracellular Ca2+ mobilization but mainly by stimulating the influx of extracellular Ca2+ via potential dependent and potential independent calcium channels.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

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

MeSH terms

  • Animals
  • Arteries / cytology
  • Arteries / drug effects*
  • Arteries / physiology
  • Calcium / metabolism
  • Endothelium / cytology
  • Endothelium / physiology
  • Extracellular Space / metabolism
  • Fishes / metabolism
  • In Vitro Techniques
  • Male
  • Neuropeptides / pharmacology*
  • Peptides / pharmacology*
  • Rats
  • Rats, Inbred Strains
  • Urotensins / pharmacology*
  • Vasoconstriction*


  • Neuropeptides
  • Peptides
  • Urotensins
  • urotensin II
  • Calcium