Differential Effects of Extracellular Mg2+ on Thrombin-Induced and Capacitative Ca2+ Entry in Human Coronary Arterial Endothelial Cells

• Published in: Arteriosclerosis, thrombosis, and vascular biology Vol. 17; no. 11; pp. 3356 - 3361
• Main Authors: Yoshimura, Mitsuisa, Oshima, Tetsuya, Matsuura, Hideo, Inoue, Toshiaki, Kambe, Masayuki, Kajiyama, Goro
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Heart Association, Inc 01.11.1997; Hagerstown, MD Lippincott
• Subjects: Biological and medical sciences; Blood vessels and receptors; Calcium - metabolism; Calcium Channel Blockers - pharmacology; Calcium Channels - drug effects; Calcium Channels - metabolism; Cell Compartmentation; Coronary Vessels - cytology; Coronary Vessels - drug effects; Coronary Vessels - metabolism; Cytosol - metabolism; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Extracellular Space; Fundamental and applied biological sciences. Psychology; Humans; Ion Transport - drug effects; Magnesium - pharmacology; Nifedipine - pharmacology; Receptors, Thrombin - drug effects; Receptors, Thrombin - metabolism; Thrombin - pharmacology; Vertebrates: cardiovascular system; Human; Cell culture; Input output; Endothelial cell; Calcium ion; Coronary artery; Magnesium ion; Exploration; Circulatory system; Extracellular
• ISSN: 1079-5642; 1524-4636
• DOI: 10.1161/01.atv.17.11.3356

Receptor-mediated and capacitative Ca entry are the primary Ca entry pathways in endothelial cells (ECs). The mechanisms for Ca entry via these pathways have not been fully elucidated. In this study, the effect of low and high external Mg concentrations on these Ca entry pathways was examined in human coronary arterial ECs. External Mg concentration did not affect cytosolic free Mg concentration. After exposure to thrombin in Ca () -free medium, addition of Ca to the medium caused a rise in cytosolic free Ca concentration ([Ca]i), indicating thrombin-induced Ca influx. Thrombin-induced Ca influx was inhibited by not only low but also high external Mg concentrations. After depletion of endoplasmic Ca stores by thapsigargin, addition of Ca to the medium induced an increase in [Ca]i, indicating capacitative Ca entry. Capacitative entry was found to be accelerated by low external Mg and inhibited by high external Mg concentration. Results suggest that receptor-mediated Ca influx requires external Mg but is inhibited by increased external Mg concentrations and that capacitative Ca entry is reduced by external Mg in human coronary arterial ECs. (Arterioscler Thromb Vasc Biol. 1997;17:3356-3361.)