Discrete intracellular Ca(2+) pools coupled to two distinct Ca(2+) influx pathways in human platelets.
Ca(2+) influx is an important event associated with platelet activation and regulated by the content of intracellular Ca(2+). Previous studies have suggested two different Ca(2+) pools and two Ca(2+) influx pathways exist in platelets. In the present study, we have investigated the regulation of thrombin- and thapsigargin-induced Ca(2+) entry into human platelets, using fluorescent indicators to monitor Ca(2+) mobilization and membrane potential. It was found that depletion of thapsigargin-sensitive Ca(2+) stores was coupled to Ca(2+) influx through a Ca(2+)-selective pathway. Additional release of Ca(2+) from the thapsigargin-insensitive pool by thrombin caused the opening of a nonselective cation channel.
Sun
B
B
Vascular Biology, Maryland Research Laboratories, Otsuka America Pharmaceutical, Inc., Rockville, MD 20878, USA. bings@mrl.oapi.com
Kambayashi
J
J
D001792:Blood Platelets / Q000378:metabolism / Q000502:physiology*; D002118:Calcium / Q000097:blood; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009532:Nickel / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology / Q000502:physiology
D002121:Calcium Channel Blockers; D007093:Imidazoles; D019284:Thapsigargin; D009532:Nickel; D013917:Thrombin; C063159:1-(2-(3-(4-methoxyphenyl)propoxy)-4-methoxyphenylethyl)-1H-imidazole; D002118:Calcium