Quantifying Brain Ammonia in Cirrhosis

A Mindray BS-200 autoanalyzer (Mindray chemistry analyzers for low-volume laboratories, Guangzhou, China) and standard commercial kits (Pars Azmun, Tehran, Iran) were used to measure serum albumin, bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) [51 (link)]. Plasma ammonia level was measured with standard kits based on the absorbance photometry method of phenate-hypochlorate reaction [52 (link)]. Brain ammonia level of cirrhotic animals was determined according to a previously reported method [44 (link)] (Table 1). Briefly, forebrain (cerebral cortex) samples (100 mg) were dissected, homogenized, and deproteinized in 3 ml of an ice-cooled (4°C) lysis solution (trichloroacetic acid, 6% w/v in double distilled water). After centrifugation (12,000 g, 10 minutes, 4°C), the supernatant was collected and neutralized (KHCO₃; 2 mol/l, pH = 7). Afterward, the ammonia content of the supernatant was measured using standard kits [52 (link)].