Serum anti-M2 mitochondrial antibody (AMA-M2) was screened with immune colloidal gold technique in 6 008 individuals aged over 60 years who underwent health check-up in Xuhui District of Shanghai,the positive samples were retested with ELISA method.The results showed that 1.31％ (79/6 008) individuals were AMA-M2 positive; the positive rate was 0.82％ (18/2 186) in males and 1.60％ (61/3 822) in females.Eleven subjects with positive AMA-M2 underwent further investigation,8 cases were diagnosed as primary biliary cirrhosis (PBC) and the remaining 3 were highly suspected as PBC.All 11 individuals were abnormal in biochemical tests of liver function and/or clinical symptoms.

Activation of the heart normally begins in the sinoatrial node (SAN). Electrical impulses spontaneously released by SAN pacemaker cells (SANPCs) trigger the contraction of the heart. However, the cellular nature of SANPCs remains controversial. Here, we report that SANPCs exhibit glutamatergic neuron-like properties. By comparing the single-cell transcriptome of SANPCs with that of cells from primary visual cortex in mouse, we found that SANPCs co-clustered with cortical neurons. Tissue and cellular imaging confirmed that SANPCs contained key elements of glutamatergic neurotransmitter system, expressing genes encoding glutamate synthesis pathway (Gls), ionotropic and metabotropic glutamate receptors (Grina, Gria3, Grm1 and Grm5), and glutamate transporters (Slc17a7). SANPCs highly expressed cell markers of glutamatergic neurons (Snap25 and Slc17a7), whereas Gad1, a marker of GABAergic neurons, was negative. Functional studies revealed that inhibition of glutamate receptors or transporters reduced spontaneous pacing frequency of isolated SAN tissues and spontaneous Ca