Determinació d’aminoàcids lliures en plasma de pacients amb ictus amb tractament trombolític

Abstract

Cerebral ischemia or stroke is a cerebrovascular disease caused by a reduction of blood flow in a certain area of the brain. It is the leading case of disability in adults and the second leading cause of death worldwide (Jin et al., 2010). The blood failure in the brain causes changes in the neuronal metabolism, such as massive entry of intra-cellular calcium, caused by a lack of oxygen and nutrients (Guevara et al., 2004). The increase of calcium intra-cytosolic enables the release of several neurotransmitters such as glutamate and nitric oxide. A high concentration of these neurotransmitters has a toxic effect on the cell, because of the stimulation of calcium entry and the release of free radicals (RLO) which has the capability to degrade proteins, nucleic acids and phospholipids (Guevara et al., 2004). Time is an essential factor in order to prevent brain damage, if a fast blood reflux happens time can prevent cell death. The recombinant plasminogenic tissue activator (rt-PA) is the only approved treatment for combating cerebral ischemia, although it has an important limitation: it is only effective up to a maximum of three hours from the beginning of the stroke (Fernandez-Gomez et al., 2008). The main goal of this study is to analyse and quantify free amino acids presented in the plasma of patients who have suffered an ischemic stroke and have been supplied with the rt-PA treatment. The aminoacids’ test is performed by a derivatization of the samples, followed by a high resolution chromatography determination in a reverse phase, with a Gemini NX-C18 column (250 x 4.4 mm) with 5μm in size of Particle and UV detection. A buffered acetate/phosphate solution, adjusted to pH 5.38, and a B acetonitrile (60%) organic solution has been used as a mobile phase. In other studies (Tcherkas et al., 2001), non treated rt-PA patients show a gradual increase on glutamate, that can reach to 15 days. The results obtained by this study prove that the rt-PA treatment has a significant effect on certain amino acids, such as glutamate, because it keeps the concentration at a stable level. These results suggest that rt-PA not only acts dissolving formed clots but also, in a molecular level, acts evading the level increase of neurotransmitters (glutamat)