The effect of Na+ on Ca2+ homeostasis in unstimulated platelets.

摘要: Abstract Platelets maintain a low cytosolic free Ca2+ concentration by limiting influx from plasma and promoting efflux. The present studies examine the role of membrane Na+ gradient in these processes. intact unstimulated platelets was altered incubating with ouabain or replacing extracellular N-methyl-D-glucamine choline. flux across amount exchangeable platelet cytosol were measured observing 45Ca2+ efflux under steady-state conditions. fluorescent probe quin2. At concentrations below 50 mM, size pool increased 48%. sequestered dense tubular system 356%. 38%. There was, however, no change total little, if any, concentration. Similar effects produced ouabain. These observations demonstrate marked influence on homeostasis platelets. nature changes, suggests that Na+/Ca2+ exchange cannot be sole basis for