Elemental maps in human allantochorial placental vessels cells: 2. MgCl2 and MgSO4 effects.
Extracellular magnesium salts are known to interfere with ionic channels in the cellular membranes. The membrane potential, a regulator of vascular tone, is a function of the physiological activities of ionic channels (particularly, K+ and Ca2+ channels in these cells). These channels regulate the ionic distribution into these cells. Micro-Particule Induced X-ray Emission (PIXE) analysis was applied to determine the ionic composition of vascular smooth muscle cells (VSMC) and of vascular endothelial cells (VEC) in the placental human allantochorial vessels in a physiological medium (Hanks' solution) modified by the addition of 2 mM MgCl2 or 2 mM MgSO4 which block the calcium-sensitive K+ channels (K(Ca)), the ATP-sensitive K+ channels (K(ATP)) and the voltage-sensitive K+ (K(df)) and Ca2+ channels. In VSMC (media layer), the addition of MgCl2 induced no modification of the K, Cl, P, S and Ca concentrations but increased the Na and Mg concentrations and the addition of MgSO4 only significantly increased the Mg concentration, the other ion concentrations remaining constant. In endothelium (VEC), MgCl2 or MgSO4 addition implicated the same observations as in VSMC. These results confirmed the blockage of K(df), K(Ca), K(ATP) and Ca channels in VSMC and VEC by magnesium salts, the relationship between Mg2+ ions and internal Na and demonstrated the possible intervention of a Na+/Mg2+ exchanger.
Centre d'Etudes Nucléaires de Bordeaux-Gradignan, Interface Physique-Biologie, Le Haut-Vigneau, BP 120, 331 75 Gradignan Cedex, France.
Claire
C
Michelet-Habchi
Philippe
P
Barberet
Raj Kumar
RK
Dutta
Philippe
P
Moretto
Andrée
A
Guiet-Bara
Michel
M
Bara
D000482:Allantois / Q000098:blood supply* / Q000737:chemistry; D002823:Chorion / Q000098:blood supply* / Q000737:chemistry; D004602:Elements; D004730:Endothelium, Vascular / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D015636:Magnesium Chloride / Q000494:pharmacology*; D008278:Magnesium Sulfate / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000737:chemistry / Q000187:drug effects; D010920:Placenta / Q000098:blood supply* / Q000737:chemistry / Q000378:metabolism; D011247:Pregnancy
D004602:Elements; D015636:Magnesium Chloride; D008278:Magnesium Sulfate