Effect of extracellular Mg2+ concentration on agonist-induced cytosolic free Ca2+ transients.
The modulating effects of extracellular Mg2+ concentration ([Mg2+]o) on vascular contraction are well known. In the present study it was tested how the changes in cytosolic free Ca2+ concentration ([Ca2+]i) induced by various agonists are modified by changes in [Mg2+]o. Extracellular Mg2+ deprivation increased the [Ca2+]i response to arginine vasopressin, to angiotensin II and to thapsigargin, but not to 5-hydroxytryptamine and noradrenaline. Withdrawal of extracellular Ca2+ revealed that extracellular Mg2+ deprivation increased Ca2+ influx, but not Ca2+ release from cellular stores. The findings demonstrate that different responses of [Ca2+]i to agonists may underlie the modulating effect of [Mg2+]o on vascular contraction.
Medizinische Universitäts-Poliklinik, University of Münster, Germany.
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Zhu
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Tepel
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Spieker
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Zidek
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D002118:Calcium / Q000032:analysis*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D016257:Fura-2; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D013729:Terpenes; D000804:Angiotensin II; D001127:Arginine Vasopressin; D019284:Thapsigargin; D008274:Magnesium; D002118:Calcium; D016257:Fura-2