Effect of Hypoxia on Ca^(2+) Concentration in Broiler's Cardiac Muscle Cells

The purpose of this research was to study the effect of hypoxia on the Ca^2＋ concentration in broiler＇s cardiac muscle cells （CMCs）. The concentration of Ca^2＋ in the CMC was observed using a laser scanning confocal microscope （LSCM）. The results showed that hypoxia could significantly increase intracellular Ca^2＋（normal oxygen, 99.3 ＋_ 13.1; hypoxia, 129.4 ＋_ 24.3, P 〈 0.01） in CMCs. The Ca^2＋ antagonist （nifedipine, verapamil） could significantly restrain the Ca^2＋ influx across the cell membrane of CMC treated by hypoxia （CMC： hypoxia ＋ verapamil, 100.9± 28.2; hypoxia ＋ nifedipine, 107.6± 27.7; P 〈 0.01）. The results showed hypoxia could increase intracellular Ca^2＋ concentration of CMC, and the Ca^2＋ antagonist could restrain the Ca^2＋ influx across the cell membrane of CMC treated by hypoxia.

The Effect of Fructose-1,6-diphosphate and HTK Solution on Protecting Primary Cardiac Muscle Cells of Rat with Cold Preservation

In this study we tried to investigate the effect of fructose-1,6-diphosphate and HTK solution on protecting primary cardiac muscle cells of rat with cold preservation. The primary cardiac muscle cells of rat were cultured in vitro with four preservation solutions respectively: 0.9 % sodium chloride solution (group A), FDP (group B), HTK solution (group C) and a mixture of FDP and HTK solution (group D). The cells were preserved for 6, 8 and 10 h at 0-4 ℃. The values of AST and LDH-L and the Na+-K+ ATPase activity in cardiac muscle cells were detected, and the survival rate of cardiac muscle cells was detected with trypan blue staining. The values of AST and LDH-L in group C and group D were remarkable lower those in group A and group B (P<0.001), while the Na+-K+ ATPase activity and the survival rate of cells in group C and group D were much higher than those in group A and group B (P<0.001). The values of AST and LDH-L after 6 hours in group D decreased much more than those in group C (P<0.01), while the Na+-K+ ATPase activity and the survival rate of cells in group D improved more than those in group C (P<0.01). Both of the HTK solution and the mixture of HTK and FDP solution have an evident effect on protecting the primary cardiac muscle cells of rat in vitro with cold preservation, Compared with the HTK solution, the mixture solution has a better short-term protective effect.

Rbfox1 controls alternative splicing of focal adhesion genes in cardiac muscle cells

Alternative splicing is one of the major cellular processes that determine the tissue-specific expression of protein variants.However,it remains challenging to identify physiologically relevant and tissue-selective proteins that are generated by alternative splicing.Hence,we investigated the target spectrum of the splicing factor Rbfox1 in the cardiac muscle context in more detail.By using a combination of in silico target prediction and in-cell validation,we identified several focal adhesion proteins as alternative splicing targets of Rbfox1.We focused on the alternative splicing patterns of vinculin(metavinculin isoform)and paxillin(extended paxillin isoform)and identified both as potential Rbfox1 targets.Minigene analyses suggested that both isoforms are promoted by Rbfox1 due to binding in the introns.Focal adhesions play an important role in the cardiac muscle context,since they mainly influence cell shape,cytoskeletal organization,and cell–matrix association.Our data confirmed that depletion of Rbfox1 changed cardiomyoblast morphology,cytoskeletal organization,and multinuclearity after differentiation,which might be due to changes in alternative splicing of focal adhesion proteins.Hence,our results indicate that Rbfox1 promotes alternative splicing of focal adhesion genes in cardiac muscle cells,which might contribute to heart disease progression,where downregulation of Rbfox1 is frequently observed.

The research of HSPB1 in apoptosis,autophagy and cardiogenic shock

Cardiogenic shock(CS)is a common cause of mortality and treatment remains challenging despite advances in therapeutic options.CS is caused by severe impairment of myocardial performance that results in decreased cardiac output,hypoperfusion of the end organ,and hypoxia.Clinically this presents as hypotension refractory to volume resuscitation with features of end-organ hypoperfusion requiring pharmacological or mechanical intervention.Acute myocardial infarction(AMI)accounts for 81%of patients with CS.Heat shock protein family B member 1(HSPB1)is a multifunctional protein induced by various stress factors and has a protective effect on cells.A large number of studies have demonstrated that HSPB1 plays an important role in regulating apoptosis.Recently,some studies have suggested that HSPB1 also participates in the autophagic process.HSPB1 are expressed in many cells of the cardiovascular system such as endothelial cells,cardiac muscle cells,monocytes,and platelets.They are up-regulated in response to inflammation,oxidative stress,or ischemia and protect cells against extracellular stress factors.Here,we explore the involvement of HSPB1 in apoptosis,autophagy,and CS.We speculate that HSPB1 may exert its anti-myocardial injury role via the regulation of apoptosis and autophagy;this may provide the basis for the development of new approaches for the prevention and treatment of CS.