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Platelet arachidonic acid metabolism in patients with cardiovascular disorders
D Ghigo1, S Treves, F Bussolino
1Dipartimento di Genetica, Biologia e Chimica Medica, Universita' di Torino, Italy.
Insights
Platelets from patients with unstable angina show increased activity in prostaglandin synthesis and calcium influx, alongside decreased sensitivity to prostacyclin. This suggests intrinsic platelet hyperactivity contributes to thrombus formation in coronary artery disease.
Area of Science:
- Cardiovascular Medicine
- Platelet Physiology
- Biochemistry
Background:
- Prostaglandins (PG) and thromboxane (Tx) are implicated in coronary artery disease pathogenesis.
- Arachidonic acid (AA) metabolism and its role in platelet function are crucial in cardiovascular health.
Purpose of the Study:
- To investigate arachidonic acid (AA) metabolism and AA-dependent calcium (Ca2+) influx in platelets from patients with unstable angina.
- To assess platelet sensitivity to prostacyclin (PGI2) in the context of unstable angina.
Main Methods:
- Compared AA metabolism via the cyclooxygenase (COx) pathway in platelets from 10 unstable angina patients and 10 controls.
- Measured hexose monophosphate shunt (HMS) activation, malonyldialdehyde (MDA) production, and AA-evoked Ca2+ flux.
- Assessed platelet sensitivity to PGI2 by measuring its effect on Ca2+ flux.
Main Results:
- Platelets from unstable angina patients showed enhanced hexose monophosphate shunt (HMS) activation in response to AA.
- Increased AA-induced malonyldialdehyde (MDA) production, AA-evoked Ca2+ flux, and glutathione-dependent peroxidase activity were observed.
- Platelet sensitivity to prostacyclin (PGI2) was significantly decreased in patients.
Conclusions:
- Evidence suggests intrinsic platelet hyperactivity at the prostaglandin (PG) peroxidase reaction in unstable angina.
- Increased prostaglandin (PG) H2 and thromboxane (Tx)A2 synthesis, coupled with reduced PGI2 sensitivity, may promote thrombus formation.
- These findings highlight potential therapeutic targets in managing unstable angina and coronary artery disease.
Abstract:
There is increasing evidence that prostaglandins (PG) and thromboxane (Tx) play a major role in the pathogenesis of coronary artery disease. The regulation of arachidonic acid (AA) metabolism through cyclooxygenase (COx) pathway and the AA-dependent Ca2+ influx were investigated in platelets from 10 patients with unstable angina and 10 controls. The activation of the hexose monophosphate shunt (HMS), a sensitive index of the flux through the PGG2 to PGH2 step of the COx pathway, in response to AA was significantly enhanced in platelets from patients. AA-induced malonyldialdehyde (MDA) production as well as AA-evoked Ca2+ flux and glutathione-dependent peroxidase activity resulted significantly increased. Moreover, platelet sensitivity to prostacyclin (PGI2), measured as inhibition of Ca2+ flux, was highly decreased. Thus far, evidence is presented for intrinsic platelet hyperactivity (at the PG-peroxidase reaction of the COx pathway) in patients with unstable angina: the resulting increase in PGH2 and TxA2 synthesis, alone or in combination with decreased PGI2 sensitivity, may account for a facilitated thrombus formation.