Altered calcium signalling in platelets from bile-duct-ligated rats.
In the present study, we have analysed the mechanisms of Ca(2+) entry and release in platelets obtained from BDL (bile-duct-ligated) rats, 11-13 days and 4 weeks after surgery. Platelets were washed and loaded with fura-2, and [Ca(2+)](i) (cytosolic Ca(2+) concentration) was determined in cell suspensions by means of fluorescence spectroscopy. Basal [Ca(2+)](i) was similar in platelets from BDL rats compared with those from their respective controls, both in the absence and presence of extracellular Ca(2+). Platelet stimulation with thrombin in the absence and presence of extracellular Ca(2+) induced a rapid rise in [Ca(2+)](i) that was of greater magnitude in platelets from BDL rats than in controls. Ca(2+) storage was significantly elevated in platelets from BDL rats, as well as the activity of SERCA (sarcoplasmic/endoplasmic-reticulum Ca(2+)-ATPase). Capacitative Ca(2+) entry, as evaluated by inhibition of SERCA with thapsigargin, was also altered in platelets from BDL rats, having lower rates of Ca(2+) entry. In conclusion, chronic BDL alters intracellular Ca(2+) homoeostasis in platelets, such that an enhanced Ca(2+) release is evoked by thrombin, which may be due to an increased amount of Ca(2+) stored in the intracellular organelles and secondary to an enhanced activity of SERCA. These alterations are already evident before cirrhosis has completely developed and occurs during the cholestasis phase.
Atucha
Noemí M
NM
Department of Physiology, Faculty of Medicine, University of Murcia, 30100 Murcia, Spain. ntma@um.es
Iyú
David
D
Alcaraz
Antonia
A
Rosa
Vladimir
V
Martínez-Prieto
Concepción
C
Ortiz
M Clara
MC
Rosado
Juan Antonio
JA
García-Estañ
Joaquín
J
D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000097:blood; D020013:Calcium Signaling; D004195:Disease Models, Animal; D006490:Hemostatics; D008105:Liver Cirrhosis, Biliary / Q000097:blood* / Q000209:etiology; D008297:Male; D015539:Platelet Activation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013917:Thrombin
D006490:Hemostatics; D013917:Thrombin; D002118:Calcium