Endothelium-dependent response of human internal mammary artery to hypoxia

P. J. Pearson, P. J. Lin, P. R.B. Evora, H. V. Schaff

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27 Scopus citations


To study the effect of hypoxia on vascular tone in human internal mammary artery (IMA), segments of IMA were suspended in organ chambers and contracted with norepinephrine (at a dose producing 30% of maximal contraction). Exposure of IMA segments with endothelium to hypoxia (partial pressure of oxygen, 38 ± 4 mmHg) resulted in a transient relaxation (47 ± 6%) followed by constriction (177 ± 8%) (n = 14). IMA segments without endothelium exhibited a gradual decrease in tension that almost completely counteracted vasoconstriction. The initial transient endothelium-dependent relaxation could be blocked by indomethacin (10-6 M) and was associated with a 51% increase in 6-ketoprostaglandin F(1α) production (n = 22, P < 0.05). The endothelium-dependent contraction to hypoxia could be attenuated by indomethacin (n = 6, P < 0.05) or N(G)-monomethyl-L-arginine (10-5 M; n = 9, P < 0.05) and was completely blocked by combination of these agonists (n = 6, P < 0.05). These experiments indicate that on exposure to hypoxia, the human IMA exhibits an initial prostacyclin-mediated relaxation followed by contraction due to the production of a constrictor prostanoid in addition to the inhibition of basal production of endothelium-derived relaxing factor.

Original languageEnglish (US)
Pages (from-to)H376-H380
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number2 33-2
StatePublished - 1993


  • N(G)-monomethyl-L- arginine
  • endothelium-derived contracting factor
  • vasospasm

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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