Effect of small changes in extracellular magnesium concentration on the tone of feline mesenteric arteries: involvement of endothelium.

Csaba Szabo, M. Faragó, E. Dóra

Research output: Contribution to journalArticle

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Abstract

The aim of this study was to investigate the effect of small alterations in extracellular magnesium concentration on the tone of feline mesenteric arteries and to examine the role of endothelium in these responses. We measured isometrical tension of isolated arterial rings, placed between two stainless steel wires in a tissue chamber containing Krebs-Henseleit solution, aerated with a gas mixture containing 95% O2 and 5% CO2 at 37 degrees C. After precontraction with noradrenaline, a decrease of extracellular magnesium concentration from 1.2 mM to 1.0 and 0.8 mM resulted in sustained relaxations, whereas the elevation of extracellular magnesium from 0.8 mM to 1.2 mM caused an increase in vascular tone when endothelium was intact. The magnesium-withdrawal related dilations were absent in endothelium-denuded vessels and were inhibited by oxyhemoglobin (5 x 10(-6) M) and methylene blue (10(-5) M), suggesting the involvement of endothelium-derived relaxing factor in this vascular response. Nifedipine (5 x 10(-7) M) or dichlorobenzamil (3 x 10(-5) M), however, did not affect the magnesium-deficiency related relaxations. Therefore, in this vascular action of magnesium, nifedipine-sensitive calcium channels or the sodium- calcium antiport system are not involved. We conclude that small alterations in extracellular magnesium concentration, possibly within the physiological range, are able to modify the basal formation and release of EDRF, and thus alter arterial smooth muscle tone in this vascular bed. This endothelium- and magnesium-dependent system appears to be more sensitive than the direct smooth muscle actions of magnesium. The possible physiological and pathophysiological consequences of these observations are discussed.

Original languageEnglish (US)
Pages (from-to)295-303
Number of pages9
JournalActa Physiologica Hungarica
Volume79
Issue number3
StatePublished - 1992
Externally publishedYes

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Mesenteric Arteries
Felidae
Magnesium
Endothelium
Blood Vessels
Nifedipine
Smooth Muscle
Magnesium Deficiency
Endothelium-Dependent Relaxing Factors
Oxyhemoglobins
Methylene Blue
Stainless Steel
Ion Transport
Calcium Channels
Dilatation
Norepinephrine
Arterial Pressure
Gases
Sodium
Calcium

ASJC Scopus subject areas

  • Physiology

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Effect of small changes in extracellular magnesium concentration on the tone of feline mesenteric arteries : involvement of endothelium. / Szabo, Csaba; Faragó, M.; Dóra, E.

In: Acta Physiologica Hungarica, Vol. 79, No. 3, 1992, p. 295-303.

Research output: Contribution to journalArticle

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