Carbonic anhydrase enzyme plays a vital role in metabolic events such as acid-base regulation and respiration. In our research, it is tried to determine the inhibitory influences of the cardiovascular therapeutics esmolol hydrochloride, amiodarone hydrochloride and lidocaine hydrochloride on human erythrocytes carbonic anhydrases (hCAI and II). In accordance with this purpose, carbonic anhydrase isoenzymes were purified from human erythrocytes by using affinity chromatography method. Enzyme purity was checked by SDS-PAGE electrophoresis method. After the aldose reductase enzymes were purified, the inhibitory affects of cardiovascular therapeutics on these enzymes, using esterase activity, which is the method of measuring in vitro activity, were examined. The three cardiovascular therapeutics dose-dependently decreased activity of hCAs. IC₅₀ values of amiodarone hydrochloride, esmolol hydrochloride and lidocaine hydrochloride were found to be, respectively, 0.91 mM, 5 mM, 5.8 mM for hCA-I and 0.41 mM, 3.5 mM, and 6.36 mM for hCA-II. Our results proved that, under in vitro conditions, cardiovascular therapeutics significantly inhibit human CA-I and II activities. So, irregular use of these medicines may cause serious adverse effects in terms of human health.

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