Inhibition of Renal Alkaline Phosphatase by Cimetidine

Dariush      Minai-Tehrani; Somayeh      Khodai; Somayeh      Aminnaseri; Saeed      Minoui; Zahra      Sobhani-Damavadifar; Sana      Alavi; Raheleh      Osmani; Shiva      Ahmadi

Abstract

Alkaline phosphatase (ALP) belongs to hydrolase group of enzymes. It is responsible for removing phosphate groups from many types of molecules, including nucleotides and proteins. Cimetidine (trade name Tagamet) is an antagonist of histamine H2-receptor that inhibits the production of gastric acid. Cimetidine is used for the treatment of gastrointestinal diseases. In this study the inhibitory effect of cimetidine on mouse renal ALP activity was investigated. Our results showed that cimetidine can inhibit ALP by uncompetitive inhibition. In the absence of inhibitor the Vmax and Km of the enzyme were found to be 13.7 mmol/mg prot.min and 0.25 mM, respectively. Both the Vmax and Km of the enzyme decreased with increasing cimetidine concentrations (0- 1.2 mM). The Ki and IC50 of cimetidine were determined to be about 0.5 mM and 0.52 mM, respectively.

Keywords: Inhibition, drug, enzyme, cimetidine, alkaline phosphatase, Pnitrophenyl phosphate (pNPP), glomerular filtration rate (GFR), creatinine, homoarginine, mercaptomethylphosphonic acid