Hyperglycemia alters cytoplasmic Ca2+ responses to capacitative Ca2+ influx in rat aortic smooth muscle cells.
Concentrations of free cytoplasmic Ca2+ in rat aortic smooth muscle (RASM) cells were monitored using the ratiometric Ca2+ indicator fura 2-acetoxymethyl ester (AM). In RASM cells cultured in 5 mM Glc, incubation with angiotensin II, ATP, or thapsigargin [a selective inhibitor of the sarcoplasmic reticulum (SR) Ca(2+)-ATPase] depleted SR Ca2+ stores and initiated a capacitative Ca2+ influx through the plasma membrane. This influx was resistant to verapamil, a selective inhibitor of L-type voltage-gated Ca2+ channels, but was sensitive to SKF-96365, an inhibitor of the receptor-operated Ca2+ entry pathway. RASM cells cultured in 25 mM Glc exhibited a significant decrease in cytoplasmic Ca2+ responses to agonist-induced Ca2+ release from SR stores and to subsequent capacitative Ca2+ entry. In addition, the cytoplasmic response to thapsigargin-induced release of Ca2+ from the SR in hyperglycemic cells peaked more sharply than in control cells and returned to baseline more rapidly. The effects of hyperglycemia were not overcome by myo-inositol supplementation.
Rivera
A A
AA
Department of Cell Biology, University of Alabama at Birmingham 35294-0005, USA.
White
C R
CR
Guest
L L
LL
Elton
T S
TS
Marchase
R B
RB
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism*; D006943:Hyperglycemia / Q000378:metabolism*; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D002121:Calcium Channel Blockers; D007093:Imidazoles; D013729:Terpenes; D000804:Angiotensin II; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D000252:Calcium-Transporting ATPases; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D002118:Calcium