AimTo investigate the effects of adiponectin on calcification in cultured cardiomyocytes via reducing endoplasmic reticulum stress-mediated apoptosis in vitro.MethodsPrimary cultured cardiomyocytes were obtained from neonatal rats by collagenase II digestion method.The α-actin expression as molecular marker of the cardiomyocytes was observed by immunocytochemistry.The cells cultured for 72 h were used in the experiment and divided into groups randomly: control group, calcified myocardial cells (CMC) group, adiponectin＋CMC (3, 10, 20, 30 mg/L) groups.The morphological changes of the cardiomyocytes were observed under phase contracted microscope.CMC was prepared by incubation with β-glycerophosphate (BGP).Calcification was confirmed by Von Kossa staining and Alizarin Red S.Calcium content and alkaline phosphatases (ALP).Alkaline phosphatase was measured by spectrophotometric measurement of p-nitorphenol release.Osteocalcin was detected by radioimmunoassay.The content of lactate dehydrogenase (LDH) was measured.The cardiomyocyte apoptosis was detected by flow cytometry.The expression levels of glucose regulated protein 78 (GRP78)/cysteine-containing aspartate-specific proteases-12 (Caspase-12)/osteoprotegerin (OPG) mRNA were detected by quantitative real-time polymerase chain reaction (qRT-PCR).ResultsThe immunocytochemical stain for smooth muscle α-actin confirmed cardiomyocytes phenotype and the multicellular nodules spontaneously