The Effects of X-Ray Contrast Media on Actin

Abstract

Most pictures made from given tissues by medical imaging equipment are usually lack of good contrast. While it is not an issue for certain examinations for the screening of many tissues low contrast difference can be a huge problem. In such cases contrast materials are very good tools to enhance the density and intensity of a vessel, body part, organ or tissue. Pharmaceutical companies develop safer contrast agents with less side-effects, so the older ionic, high osmolality compounds have been replaced by non-ionic, low osmolality contrast materials. It is clear from certain publications that these contrast agent molecules easily penetrate in cells of different tissues and because of their limited ability of depletion these molecules can accumulate in cells of many different tissues. The overview of the corresponding literature clarifies that the effects of the clinically applied contrast materials expressed directly on the actin cytoskeleton and the detailed molecular mechanisms are unknown. Our aim is to investigate the effects of the latest contrast agents on the actin cytoskeleton. Primarily we want to focus on the investigations of any effects contrast materials can cause on the actin protein itself (structural change, loss of function, changed affinities for nucleotides, change in average filament length, etc.) and on the dynamic organisation/rearrangement of the actin network. Our first results show dramatic effects caused by the applied contrast materials on the polymerisation properties of actin. The examined contrast compounds (Iomeprol, Iobitridol) decreased the rate of actin polymerisation by 3-fold. The way of binding of substance molecules to actin is not clear yet, but our DSC results show that the thermal stability of actin filaments is significantly decreased in the presence of contrast agents.