Platelet membrane fluidity and intraplatelet Ca2+ mobilization are affected in uraemia.
In present investigations, platelet membrane fluidity and intraplatelet Ca2+ mobilization were analysed in uraemic platelets by fluorescence techniques. Thirteen non-dialyzed uraemic patients and 16 control subjects were examined. Anisotropy of DPH-probe, measured at 37 degrees C, was significantly higher in control (0.2236 +/- 0.0050) than in uraemic platelets (0.1969 +/- 0.0082; p < 0.01). There was no difference between control (109.8 +/- 6.0 nM) and uraemic platelets (100.0 +/- 7.3 nM) when the basal [Ca2+]i in resting platelets was determined. Activation of platelets by ADP (12.5 microM) or by thrombin (0.1 U/ml) resulted in an increase in [Ca2+]i. It was significantly higher (p* < 0.003 for ADP and p* < 0.009 for thrombin, respectively) in control platelets (383.6 +/- 56.3 nM and 2031.0 +/- 298.8 nM, respectively) than in uraemic ones (191.0 +/- 21.3 nM and 838.7 +/- 144.1 nM, respectively). The amount of released Ca2+ was higher in control platelets activated by both ADP and thrombin (157.6 +/- 21.4 nM and 409.3 +/- 71.0 nM, respectively) than in uraemic platelets (76.7 +/- 15.7 nM and 203.0 +/- 29.3 nM, respectively) and the differences were significant (p < 0.01 and p* < 0.01, respectively). These results indicate an abnormal intracellular Ca2+ mobilization in uraemic platelets. Both increased membrane fluidity and decreased Ca2+ mobilization should be considered as a possible reason of reduced fibrinogen receptor exposure on uraemic platelets.
Walkowiak
B
B
Department of Biophysics, Medical University of Lodz, Poland. bogdan01.@psk2.am.lodz.pl
Borkowska
E
E
Koziolkiewicz
W
W
Michalec
L
L
Sobol
A
A
Cierniewski
C S
CS
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D003404:Creatinine / Q000097:blood; D006801:Humans; D008560:Membrane Fluidity / Q000502:physiology*; D008875:Middle Aged; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood; D014511:Uremia / Q000097:blood / Q000503:physiopathology*
D000244:Adenosine Diphosphate; D012964:Sodium; D003404:Creatinine; D011188:Potassium; D002118:Calcium