Platelets activation processes comprise very complex signalling pathways which involve a G protein system, coupled to effect enzymes such as phospholipase A2, phospholipase C, guanilil and adenilil cyclases. Closely related functional properties and special estructural characteristics of platelets confer them a very high trombogenic potential, which play a role in the development of stroke, from the primary hemostasis. Basis of platelet aggregation, activation, degranulation and platelet participation in cerebrovascular disease were reviewed. Usage of antiplatelet agents, and novel anti-membrane-glycoproteins therapies were emphasized.
Stroke
Accidente Cerebrovascular en poblaciones situadas a grandes alturas: Revisión y análisis de los factores de riesgo.
Despite our understanding about cerebrovascular accident, also known as stroke, its risk factors, treatment and prevention, it remains the leading cause of death of both men and women worldwide. Several risk factors have been associated with higher incidence of stroke such as systolic or diastolic hypertension, diabetes, hypercholesterolemia, cigarette smoking or obesity. Other such as cocaine abuse, heavy alcohol consumption, AIDS, Vitamin D and protein C deficiency are also important non traditional risk factors, associated with increased prevalence of stroke. Nevertheless, high altitude exposure and potential impact of hypoxia as a stroke risk factor –in people living or visiting high altitude environments– has not been clearly established yet. This review will analyze the available evidence concerning about the association of risk factors with higher prevalence of stroke during acute or chronic high altitude exposure, either in high altitude dwellers or new sojourners. The author will examine the available evidence behind the possible physiopathology of ischemic and hemorrhagic stroke in those living at high altitudes. We conclude that living or visiting high altitude locations is a potential non traditional risk factor associated with higher incidence of ischemic stroke, especially in young otherwise healthy men. The hypobaric hypoxia level or the altitude in which stroke commonly starts is very difficult to establish. However, it is well known that as soon as hypoxia causes acclimatization, risk becomes higher. The evidence suggests that high altitude exposure and consequent hypobaric hypoxia are important environmental factors to be considered. The time length of exposure, high levels of hematocrit and polycythemia are the most prevalent risk factors associated with higher incidence of stroke in subjects exposed to chronic or acute hypoxia.
