The calcium-sensing receptor (CaSR) is a G protein-coupled receptor (GPCR) that activates intracellular effectors; for example, it causes inositol phosphate (IP) and 1,2 diacylglycerol (DAG) accumulation, stimulating the release of intracellular calcium and the activation of the protein kinase Cs (PKCs). The activation of CaSR by ischemia/reperfusion (I/R) induces cardiomyocyte apoptosis through the mitochondrial apoptotic pathway; however, the underlying mechanisms remain unclear. In this study, rat hearts were subjected to 30 min of ischemia followed by 2 h of reperfusion in the presence of a CaSR activator, GdCl(3). Our results revealed that, under these conditions, the expression of CaSR was increased, the number of apoptotic cardiomyocytes was significantly increased (as shown by terminal deoxy-nucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay) and the cells with a typical apoptotic morphology were observed using transmission electron microscopy. Our data further showed that mitochondria isolated from hearts that had undergone I/R combined with GdCl(3) exhibited a significant increase in the translocation of phosphorylated PKCδ to the mitochondria, an increase in cytochrome c (cyt c) release from the mitochondria and a marked decrease in mitochondrial potential. The administration of rottlerin, an inhibitor of PKCδ, significantly reduced reperfusion-induced apoptosis, phospho-PKCδ translocation to the mitochondria and the release of cyt c from the mitochondria. Thus, the involvement of CaSR in cardiac apoptosis through the mitochondrial pathway during I/R with GdCl(3) is related to phospho-PKCδ translocation to the mitochondria.

To investigate the injury and pathogenesis of Clonorchis sinensis (C. sinensis) to hepatocytes, the liver samples from Wistar rats and patients with C. sinensis infection were examined. The typical histopathological findings of clonorchiasis were observed in rats 4 to 12 weeks postinfection, and majority hepatocytes exhibited hydropic degeneration, even some hepatocytes showed densely condensed nuclei suggesting apoptosis in liver tissue. Apoptosis was found around the central vein or portal areas of liver tissue in rat infected with C. sinensis by transferase uridyl nick end labeling (TUNEL) assay. Compared with normal control, TUNEL-positive cells in liver tissue increase from 4 to 12 weeks postinfection with the peak at 8 weeks. Furthermore, the expression of mRNA and protein of Fas, FasL, and caspase-3 was stronger in infected group than normal control using semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. Autopsy specimens from four patients infected with C. sinensis have the same findings detected by histopathology, TUNEL, and immunohistochemistry. These findings suggest that the C. sinensis can stimulate both hepatocytic apoptosis and hydropic degeneration that may be responsible for relationship between clinical manifestations and liver lesions in patients with clonorchiasis. These data also indicate a role for Fas/FasL-mediated pathway in the apoptosis that occurs in response to C. sinensis infection.

Our previous studies demonstrated that caclium-sensing receptor (CaR) stimulation elicited phospholipase C (PLC)-mediated inositol triphosphate (IP(3)) formation, leading to an elevation in [Ca(2+)](i) released from the endo(sarco)plasmic reticulum (ER) to induce ER stress and perturbations of ER function, which cause cardiomyocyte apoptosis during ischemia/reperfusion (I/R). The aim of this study was to determine whether the protection of post-conditioning (PC) from I/R heart injury involved relieving calcium-sensing receptor (CaR)-induced ER stress. Male Wistar rats were subjected to 30 min of ischemia followed by 2 h of reperfusion. The rats were post-conditioned after the 30 min of ischemia by three cycles of 10 s of reperfusion followed by 10 s of ischemia at the onset of reperfusion. Meanwhile, GdCl(3), an activator of CaR, and NPS-2390, a specific inhibitor, were administered. We found that the PC and PC with NPS-2390 groups improved the recovery of cardiac function during reperfusion compared to the IR and PC groups with GdCl(3), respectively. [Ca(2+)](i) and [Ca(2+)](ER) were determined using Fluo-4 AM and Fluo-5N AM, respectively, using laser confocal microscopy. [Ca(2+)](i) was significantly increased, whereas [Ca(2+)](ER) was significantly decreased in the I/R and PC groups with GdCl(3). The rate of apoptotic cells was significantly decreased as shown by TUNEL (Terminal deoxy-nucleotidyl transferase-mediated dUTP nick end labeling) assay in PC and PC with NPS-2390 groups compared to the I/R and PC groups with GdCl(3). In the I/R and PC groups with GdCl(3), the activated fragments of caspase-12, the cleavage products of activating transcription factor 6 (ATF6) and phospho-JNK (c-Jun NH(2)-terminal kinase) were increased compared to the PC and PC with GdCl(3) groups. These results demonstrated that PC could protect the myocardium from I/R injury by inhibiting CaR-induced sarcoplasmic reticulum stress.

Whether bone marrow changes occur and potentially contribute to the hematological abnormalities in liver cirrhosis remain unclear. In this study, we established a rat model of liver cirrhosis induced by carbon tetrachloride. Electron microscopy examination showed focal lesions in bone marrow sinusoidal endothelium and hematopoietic cells in animals with cirrhosis. With the persistence of liver cirrhosis, injuries of bone marrow sinusoidal endothelium progressed from mild mitochondrial changes to nuclear pycnosis and cell disruption, and the trilineage hematopoietic cells showed apoptosis and necrosis. Immunohistochemistry revealed increased expression of E-selectin, P-selectin and vWF in bone marrow sinusoidal endothelium of the cirrhotic rats, which was consistent with the data from semiquantitative reverse transcriptase-polymerase chain reaction analysis. Autopsy specimens from patients with liver cirrhosis (in the absence of other disease) showed the same findings as detected by immunohistochemistry in animal models. The results provide evidence of the association between liver cirrhosis and bone marrow alterations by demonstrating the bone marrow sinusoidal endothelium lesions in both a rat model and patients. It also indicates that activation or injury of bone marrow sinusoidal endothelium mediated by E-selectin, P-selectin, and vWF might have a role in pathogenesis of bone marrow changes during liver cirrhosis. The lesions of bone marrow sinusoidal endothelium might contribute to the hematological abnormalities in the end stage of liver disease.

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