Las prostaglandinas (PGs) y los tromboxanos (TXs) juegan un papel esencial en la fisiopatologia cardiovascular. Estos prostanoides son sintetizados a traves de la accion enzimatica de las ciclooxigenasas (COXs) sobre el acido araquidonico, lo que lleva a la produccion de un intermediario inestable, la PGH2, a partir de la cual diversas sintetasas e isomerasas generaran las diferentes prostaglandinas y tromboxanos (PGE2, PGD2, PGI2, PGF2�¿ and TXA2). Existen dos ciclooxigenasas bien caracterizadas denominadas COX-1 y COX-2, con diferentes propiedades. COX-1 se expresa constitutivamente en la mayoria de los tejidos, estando implicada en la biosintesis de prostanoides con funciones homeostaticas. Por otro lado, la expresion de COX-2 se induce en respuesta a mitogenos y estimulos pro-inflamatorios, constituyendo la isoforma predominantemente implicada en la respuesta inflamatoria.
Los prostanoides modulan la patogenesis de enfermedades vasculares como la trombosis y la aterosclerosis a traves de una serie de procesos como: la agregacion plaquetaria, la vasodilatacion y vasoconstriccion, y la respuesta inflamatoria local.
Multiples estudios han demostrado la importancia de las acciones mediadas por los prostanoides en la fisiopatologia cardiovascular, bien mediante el uso de inhibidores farmacologicos o a traves del analisis de ratones geneticamente deficientes. Sin embargo, la reciente retirada del mercado de inhibidores selectivos de COX-2 a causa de sus efectos adversos en pacientes con riesgo cardiovascular, ha abierto el debate sobre el papel de los prostanoides en la patologia vascular y sobre las ventajas o inconvenientes del uso de inhibidores de COXs en las enfermedades cardiovasculares
Prostaglandins (PGs) and thromboxanes (TXs) play a pivotal role in cardiovascular physiopathology. They are synthesized from arachidonic acid by the enzymatic action of cyclooxygenases (COXs), leading to the production of an unstable intermediate, PGH2 that is subsequently converted to the different prostaglandins and thromboxanes (PGE2, PGD2, PGI2, PGF2á and TXA2) by the action of different synthases and isomerases. There are two well characterized COX enzymes, termed COX-1 and COX-2, with different properties. While COX-1 is expressed constitutively in most tissues and is thought to be involved in homeostatic prostanoid biosynthesis, COX-2 is transcriptionally up-regulated in response to mitogens and pro-inflammatory stimuli being the predominant isoform involved in the inflammatory response.
In the cardiovascular system, prostanoids have been shown to modulate the pathogenesis of vascular diseases as thrombosis and atherosclerosis through a variety of processes, including platelet aggregation, vasorelaxation and vasoconstriction, local inflammatory response and leukocyte-endothelial cell adhesion. Multiple studies using pharmacological inhibitors and genetically deficient mice have demonstrated the importance of prostanoid-mediated actions on cardiovascular physiology. However, recent withdrawal of COX-2 selective inhibitors from the clinic because of their adverse effects in patients with potential cardiovascular risk has opened a debate about the role of COX�derived prostanoids in vascular pathologies and the benefits and risks for the use of COX inhibitors in cardiovascular diseases
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