Platelet calcium homeostasis is abnormal in patients with severe arteriosclerosis.
To evaluate platelet calcium homeostasis in a typical thrombosis-prone clinical condition, 14 patients with severe arteriosclerosis and 11 healthy control subjects were studied. Platelet intracellular free calcium concentration ([Ca2+]i) was evaluated by means of the fluorescent probe fura 2 under resting conditions and after challenge with 0.05, 0.1, and 0.5 U/mL thrombin (final concentrations). Three different concentrations of extracellular ionized calcium ([Ca2+]e) were used: 1 mmol/L, 1 mumol/L, and < 1 nmol/L. Resting platelet [Ca2+]i was significantly higher (P < .001) in patients than in control subjects. After addition of 0.05 U/mL thrombin, the relative increase of [Ca2+]i was lower in patients than in control subjects in each of the three [Ca2+]e conditions (P = .05 at 1 mmol/L, P = .02 at 1 mumol/L, and P = .04 at < 1 nmol/L). After addition of 0.1 U/mL thrombin, the relative increase of [Ca2+]i was lower in patients than in control subjects under two [Ca2+]e conditions, 1 mumol/L and < 1 nmol/L (P = .04 and P = .03 respectively). With 0.5 U/mL thrombin, a trend toward lower values in patients than in control subjects was observed, reaching statistical significance (P = .03) only at < 1 nmol/L [Ca2+]e. These results suggest that calcium homeostasis is abnormal in platelets from patients with severe arteriosclerosis and probably reflects a chronic activation.
Vicari
A M
AM
Department of Medicine, IRCCS H. San Raffaele, Milan, Italy.
Monzani
M L
ML
Pellegatta
F
F
Ronchi
P
P
Galli
L
L
Folli
F
F
D000328:Adult; D000368:Aged; D001161:Arteriosclerosis / Q000097:blood*; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000097:blood*; D005260:Female; D005456:Fluorescent Dyes; D016257:Fura-2; D006706:Homeostasis; D006801:Humans; D008297:Male; D008875:Middle Aged; D013917:Thrombin / Q000494:pharmacology
D005456:Fluorescent Dyes; D013917:Thrombin; D002118:Calcium; D016257:Fura-2