Vasoconstriction induced by zooxanthellatoxin-B, a polyoxygenated long- chain product from a marine alga

Takahiro Moriya, Yukisato Ishida, Hideshi Nakamura, Tohru Asari, Akio Murai, Yasushi Ohizumi

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


We found that zooxanthellatoxin-B from a symbiotic marine alga, Symbiodinium sp., caused a concentration-dependent contraction of the rabbit isolated aorta at concentrations of 10-7 10-5 M. Verapamil (10-6 M) and mefenamic acid (10-5 M) significantly attenuated the contractile response to zooxanthellatoxin-B at lower concentrations (10-7 - 10-6 M) but not at higher concentrations (3 X 10-610-5 M). The response to zooxanthellatoxin-B was partly inhibited by phentolamine (10-6 M), whereas it was potentiated by ouabain (10-5 M). Tetrodotoxin (10-6 M), methysergide (10-6 M), chlorpheniramine (10-6 M) or indomethacin (3 X 10-6 M), however, did not affect it. The zooxanthellatoxin-B-induced contraction was abolished by incubation in Ca2+-free solution. The contractile response increased in a concentration-dependent fashion with Ca2+ (0.03 and 10 mM) or Sr2+ (0.10 and 10 mM). After treatment with verapamil (10-6 or 5 X 10-6 M), the concentration-contractile response curves for Ca2+ and Sr2+ in the presence of zooxanthellatoxin-B were shifted to the right in parallel. MgCl2 (10 mM) shifted the concentration- response curve for Ca2+ more markedly than did verapamil. Zooxanthellatoxin-B increased tissue Na+ and reduced tissue K+ contents in the aorta, suggesting that zooxanthellatoxin-B increases Na+ and K+ permeability across the plasma membrane. These results suggest that the zooxanthellatoxin-B-induced contraction of the aorta is caused mainly by a direct action on smooth muscle, i.e., an increase in Ca2+ permeability that occurs at least partly through voltage-sensitive Ca2+ channels as well as through nonselective cation channels in the cell membrane of smooth muscle.

Original languageEnglish
Pages (from-to)59-65
Number of pages7
JournalEuropean Journal of Pharmacology
Issue number1
Publication statusPublished - 1998 May 29
Externally publishedYes


  • Aorta
  • Ca channel
  • Contraction
  • Rabbit
  • Smooth muscle
  • Zooxanthellatoxin-B

ASJC Scopus subject areas

  • Pharmacology


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