Role of endothelium in the response of the vein wall to magnesium withdrawal

Csaba Szabó, Viktor Bérczi, Ferenc Schneider, Arisztid G.B. Kovách, Emil Monos

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


Complete absence of magnesium has a two-fold effect on the arterial tone: direct smooth muscle contraction and relaxation via endothelium-derived relaxing factor (EDRF) release. In the present study performed on a systemic vein we investigated (1) which of these effects dominates following reduction of magnesium concentration from 1.2 mM to 0.8 and 0.4 mM and (2) whether the vessel segments asymmetrically respond when the magnesium concentration is reduced on either the intra- or extraluminal side. The effects of reducing magnesium concentration on both the isometric tension of isolated ring preparations and the diameter of isolated, perfused and superfused feline femoral veins were investigated. In nor-adrenaline-precontracted rings, rapid decreases in the extracellular magnesium concentration from 1.2 mM to 0.8 and 0.4 mM caused relaxation, whereas total omission of magnesium returned the tone to the level of the initial tone induced by noradrenaline. Both in the presence of haemoglobin (5×10-6M), and in vessels without endothelium, lowering the magnesium concentration caused a dose-dependent elevation of the noradrenaline-induced tone. In perfused and superfused noradrenaline-contracted vein segments, each reduction of extraluminal magnesium concentration caused contraction of the vessels, regardless of whether the endothelium was intact or not. A decrease in intraluminal magnesium concentration did not alter the diameter of the vessel when the endothelium was intact, but caused contraction when the endothelium was disrupted. The results of the present study demonstrate that both the reduction of magnesium concentration or its complete absence cause an EDRF-mediated relaxation and a directly mediated smooth muscle contraction in the femoral vein of the cat. Within the physiological range of extracellular magnesium concentrations, however, the EDRF-mediated relaxation seems to dominate.

Original languageEnglish (US)
Pages (from-to)140-145
Number of pages6
JournalPflügers Archiv European Journal of Physiology
Issue number2
StatePublished - Feb 1992
Externally publishedYes


  • Basal release of endothelium-derived relaxing factor
  • Femoral vein
  • Smooth muscle tone

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)


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