Tributyltin (TBT) effects at a vascular level

• Autor(a) principal: Barros, Ana Rodrigues
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/16393
• topic: Toxicologia e ecotoxicologia; Compostos orgânicos do estanho; Tributilestanho - Toxicidade; Compostos organometálicos

Organotins are an important class man made organometallic compounds and tributyltin (TBT) is one of the most studied chemicals within this class. TBT is a potent endocrine disruptor being also considered as an obesogenic, immunotoxic and neurotoxic compound. Humans were exposed to this and other organotin compounds as a consequence of their widespread commercial applications including plastic stabilizers, catalytic agents and industrial biocides. Their utilization as catalytic agents in the production of silicones leads to the presence of these chemicals in silicone based products including those used in biomedical applications such as breast implants and cardiac valves which may constitute a potential source of exposure. According to the World Health Organization cardiovascular diseases are sharply increasing and constitute the prime cause of death globally. Taking this into account, regulatory agencies, recommend the study of organotin compounds toxicity. Considering the limited number of studies on the cardiovascular effects of organotins, the present thesis aims to elucidate the effects of TBT at the vascular level. The study of TBT effect on the contractility of rat artery (aorta) was performed by the organ bath technique and the L-type calcium channels in A7r5 (cell line derived from the smooth muscle of embryonic rat aorta) was measured by whole-cell configuration of the patch clamp technique. The obtained results demonstrated that TBT seems to relax the rat aorta without endothelium contracted by noradrenaline and potassium chloride but this effect is not significantly different from the respectively ethanol control. The electrophysiological experiments demonstrated that the inhibition of the calcium current by the L-type calcium channels in the A7r5 vascular smooth muscle cells was also not significantly different, which suggests that probably the mode of action of TBT is more complex and involves other pathways.