Contractile and endothelium-dependent dilatory responses of cerebral arteries at various extracellular magnesium concentrations

Mária Faragó, Csaba Szabo, Eörs Dóra, Ildikó Horváth, Arisztid G B Kovách

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

To clarify the effect of extracellular magnesium (Mg2+) on the vascular reactivity of feline isolated middle cerebral arteries, the effects of slight alterations in the Mg2+ concentration on the contractile and endothelium-dependent dilatory responses were investigated in vitro. The contractions, induced by 10-8-10-5 M norepinephrine, were significantly potentiated at low Mg2+ (0.8 mM v. the normal, 1.2mM). High (1.6 and 2.0 mM) Mg2+ exhibited an inhibitory effect on the contractile responses. No significant changes, however, in the EC50 values for norepinephrine were found. The endothelium-dependent relaxations induced by 10-8-10-5 M acetylcholine were inhibited by high (1.6 and 2.0 mM) Mg2+. Lowering of the Mg2+ concentration to 0.8 mM or total withdrawal of this ion from the medium failed to alter the dilatory potency of acetylcholine. The changes in the dilatory responses also shifted the EC50 values for acetylcholine to the right. The present results show that the contractile responses of the cerebral arteries are extremely susceptible to the changes of Mg2+ concentrations. In response to contractile and endothelium-dependent dilatory agonists, Mg2+ probably affects both the calcium influx into the endothelial and smooth muscle cells as well as the binding of acetylcholine to its endothelial receptor. Since Mg2+ deficiency might facilitate the contractile but not the endothelium-dependent relaxant responses, the present study supports a role for Mg2+ deficiency in the development of the cerebral vasospasm.

Original languageEnglish
Pages (from-to)161-164
Number of pages4
JournalJournal of Cerebral Blood Flow and Metabolism
Volume11
Issue number1
StatePublished - 1991
Externally publishedYes

Fingerprint

Cerebral Arteries
Magnesium
Acetylcholine
Endothelium
Norepinephrine
Intracranial Vasospasm
Felidae
Middle Cerebral Artery
Smooth Muscle Myocytes
Blood Vessels
Ions
Calcium

Keywords

  • Acetylcholine
  • Cerebrovascular smooth muscle
  • Contraction
  • Endothelium-dependent relaxation
  • Extra-cellular magnesium
  • Norepinephrine

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism
  • Neuroscience(all)

Cite this

Contractile and endothelium-dependent dilatory responses of cerebral arteries at various extracellular magnesium concentrations. / Faragó, Mária; Szabo, Csaba; Dóra, Eörs; Horváth, Ildikó; Kovách, Arisztid G B.

In: Journal of Cerebral Blood Flow and Metabolism, Vol. 11, No. 1, 1991, p. 161-164.

Research output: Contribution to journalArticle

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AB - To clarify the effect of extracellular magnesium (Mg2+) on the vascular reactivity of feline isolated middle cerebral arteries, the effects of slight alterations in the Mg2+ concentration on the contractile and endothelium-dependent dilatory responses were investigated in vitro. The contractions, induced by 10-8-10-5 M norepinephrine, were significantly potentiated at low Mg2+ (0.8 mM v. the normal, 1.2mM). High (1.6 and 2.0 mM) Mg2+ exhibited an inhibitory effect on the contractile responses. No significant changes, however, in the EC50 values for norepinephrine were found. The endothelium-dependent relaxations induced by 10-8-10-5 M acetylcholine were inhibited by high (1.6 and 2.0 mM) Mg2+. Lowering of the Mg2+ concentration to 0.8 mM or total withdrawal of this ion from the medium failed to alter the dilatory potency of acetylcholine. The changes in the dilatory responses also shifted the EC50 values for acetylcholine to the right. The present results show that the contractile responses of the cerebral arteries are extremely susceptible to the changes of Mg2+ concentrations. In response to contractile and endothelium-dependent dilatory agonists, Mg2+ probably affects both the calcium influx into the endothelial and smooth muscle cells as well as the binding of acetylcholine to its endothelial receptor. Since Mg2+ deficiency might facilitate the contractile but not the endothelium-dependent relaxant responses, the present study supports a role for Mg2+ deficiency in the development of the cerebral vasospasm.

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