Acute liver failure is a multisystem disorder associated with acute renal failure, hypotension, sepsis, coagulopathy, encephalopathy, and cerebral edema [
1]. Some researchers have considered that a few hepatocytes are required to restore the liver mass after profound liver injury, while other liver-repopulation and transplantation studies have indicated that bone-marrow stem cells might have the capacity to differentiate into hepatocytes [
2‐
5]. However, the regenerative capacity is insufficient after chronic liver injury [
6]. Currently, most researchers consider that the activation, proliferation, migration, differentiation, and survival of cells in the regenerating liver are controlled by a large number of growth factors and cytokines, which expressed at the sites of injury or reach the liver via the circulatory system [
7]. Furthermore, a recent study found that severe lactic acidosis was harmful for cirrhotic patients [
8]. Our preclinical studies showed that the clinical symptoms of some patients with liver failure, who did not present with symptoms of hepatic encephalopathy (HE) and were treated with blood ammonia-lowering drugs, were greatly relieved. The primary disease process in the liver is complicated because of numerous metabolic disturbances throughout the body [
9]. Therefore, we inferred that a reduction in the blood ammonia level could promote the functions of synthesis, secretion, and transformation in liver cells and simultaneously relieve the damage to liver cells. Recent studies showed that increasing ammonia concentrations had deleterious effects on the functions of the central nervous system and the elevation of arterial ammonia was associated with high mortality in patients with acute liver failure [
10,
11]. Ammonia is a neurotoxin involved in the pathogenesis of neurological disease associated with hyperammonia [
12]. Hyperammonia following acute and chronic liver diseases may lead to HE, which is accompanied by the failure of energy metabolism [
13], disturbances of neurotransmission in the brain, and changes in Na
+-K
+-ATPase [
14,
15]. Moreover, our study showed that there was no change in Na
+-K
+-ATPase using gene chip assays, but arginine disappeared. Although the liver can convert ammonia to nontoxic urea through the urea cycle [
16], the urea synthesis capacity is reduced in patients with liver disease, leading to a reduced capacity to detoxify ammonia in the liver. Besides, hyperammonia is also produced in urea cycle disorders and other conditions leading to either defective ammonium removal or overproduction of ammonium beyond the capacity of liver clearance [
17]. Therefore, we thought that ammonia might induce liver injury through another mechanism. However, there are few reports about whether increasing blood ammonia can lead to the damage of hepatocyte function observed in the present study. We also found that NH
4Cl induced specific liver injury compared with other cell types and apoptosis of primary hepatocytes was significantly increased compared with control cells. In this study, we hypothesized that hyperammonia might directly induce a series of changes leading to liver injury. To verify this assumption, a hyperammonia cell model was established to investigate the effects of NH
4Cl on liver damage and further examine the effects of NH
4Cl on hepatocyte apoptosis.