Influence of low density lipoproteins on cytosolic free Ca2+ concentration and dense tubular system in human platelets.
The cytosolic free Ca2+ concentration [Ca2+]i and dense tubular system (DTS) of washed human platelets were affected by low density lipoproteins (LDL) of 25 micrograms/ml at 37 degrees C for 10 minutes. After the incubation with LDL, the [Ca2+]i increased from 115 +/- 29 nM to 141 +/- 24 nM. LDL promoted the increase of [Ca2+]i (471 +/- 31 nM) induced by thrombin (0.03 U/ml) as compared to that which thrombin did alone (240 +/- 11 nM) (p < 0.05). The increased Ca2+ influx from the extracellular space is thought to be the reason of the increase in [Ca2+]i, since the effect of LDL was abolished by removal of external Ca2+ by EGTA. The DTS changed primarily from thin elongated forms to rounded vesicles. No evidence was noticed that LDL caused a mobilization of Ca2+ from the DTS.
Zhao
B
B
Institute of Anatomy, University of Münster, Germany.
Dierichs
R
R
Liu
J F
JF
Zhu
Z M
ZM
Berkes
P
P
Frye
S
S
D001692:Biological Transport / Q000187:drug effects; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D002118:Calcium / Q000378:metabolism*; D002451:Cell Compartmentation / Q000187:drug effects; D003600:Cytosol / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000187:drug effects; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D015539:Platelet Activation; D015398:Signal Transduction / Q000187:drug effects; D013917:Thrombin / Q000494:pharmacology
D008077:Lipoproteins, LDL; D004492:Edetic Acid; D013917:Thrombin; D002118:Calcium