Potentiation of the intracellular Ca2+ response to arginine vasopressin by increased cytosolic-free Mg2+ in rat vascular smooth muscle cells.
Although the inhibitory effects of extracellular Mg2+ on Ca2+ influx are well established, little is known about the effects of intracellular Mg2+ on Ca2+ handling. In the present study, the effects of cytosolic-free Mg2+ concentration in the physiological (submillimolar) range on Ca2+ handling were investigated after stimulation of rat vascular smooth muscle cells with arginine vasopressin. Cytosolic Mg2+ was manipulated by culturing cells in medium containing different Mg2+ concentrations. Peak cytosolic-free Ca2+ concentration responses to arginine vasopressin (1 mumol/1) were measured in the presence and absence of external Ca2+. The results suggest that an increase in cytosolic-free Mg2+ concentration increases both Ca2+ discharge from intracellular stores and Ca2+ influx, whereas a decrease in intracellular Mg2+ attenuates Ca2+ influx.
Yoshimura
M
M
First Department of Internal Medicine, Hiroshima University School of Medicine, Japan.
Oshima
T
T
Matsuura
H
H
Ishida
T
T
Kambe
M
M
Kajiyama
G
G
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D005470:Fluorometry; D016257:Fura-2 / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism*; D008297:Male; D008345:Manganese / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D000889:Anti-Arrhythmia Agents; D013729:Terpenes; D001127:Arginine Vasopressin; D008345:Manganese; D019284:Thapsigargin; D008274:Magnesium; D002118:Calcium; D016257:Fura-2