1. @entity1 platelets respond to agonists of G protein (G(q))-coupled receptors by generating an irregular pattern of spiking changes in cytosolic @entity141 ([ @entity141 ]i). We have investigated the @entity857 -induced @entity141 responses of single, @entity3576 -loaded platelets in the presence or absence of autologous plasma or whole blood under flow conditions. 2. In plasma-free platelets, incubated in buffer medium, baseline separated [ @entity141 ]i peaks always consisted of a rapid rising phase (median time 0.8 s) which was abruptly followed by a slower, mono-exponential decay phase. The decay constant differed from platelet to platelet, ranging from 0.23 +/- 0.02 to 0.63 +/- 0.03 s(-1) (mean +/- S.E.M., n = 3-5), and was used to identify individual @entity141 release events and to determine the @entity141 fluxes of the events. 3. Confocal, high-frequency measurements of adherent, spread platelets (diameter 3-5 microm) indicated that different optical regions had simultaneous patterns of both low- and high-amplitude @entity141 release events. 4. With or without plasma or flowing blood, the @entity857 -induced @entity141 signals in platelets had the characteristics of irregular @entity141 puffs as well as more regular @entity141 oscillations. Individual [ @entity141 ]i peaks varied in amplitude and peak-to-peak interval, as observed for separated @entity141 puffs within larger cells. On the other hand, the peaks appeared to group into periods of ragged, shorter-interval @entity141 release events with little integration, which were alternated with longer-interval events. 5. We conclude that the spiking @entity141 signal generated in these small cells has the characteristics of a 'poor' oscillator with an irregular frequency being reactivated from period to period. This platelet signal appears to be similar in an environment of non-physiological buffer medium and in flowing, whole blood.

Ragged spiking of free calcium in XXXX -stimulated @entity1 platelets: regulation of puff-like calcium signals in vitro and ex vivo.

@entity1 :: ('9606', 'Species') :: ['Human'] @entity141 :: ('CHEBI:29108', 'Chemical') :: ['Ca2+'] @entity857 :: ('MESH:D000244', 'Chemical') :: ['ADP'] @entity3576 :: ('MESH:C059715', 'Chemical') :: ['Fluo-3']
@entity857 :: (MESH:D000244,Chemical) :: ['ADP']
