ABSTRACT
<p><b>OBJECTIVE</b>To construct plasmid expressing pacemaker gene pIRES2-EGFP-HCN2 and study its effects in transfected atrial myocytes in vitro and in canine model of sick sinus syndrome (SSS).</p><p><b>METHODS</b>mHCN2 gene was isolated from PTR plasmids and cloned into eukaryotic expression plasmid pIRES2-EGFP. Recombinant plasmids pIRES2-EGFP-HCN2 was transfected with by electroporation into neonatal atrial cardiomyocytes or injected to the sinoatrial (SA) region of canines with SSS induced by catheter and chemical ablation. pIRES2-EGFP-HCN2 expression was detected under fluorescence microscope and confirmed by reverse transcription-polymerase chain reaction (RT-PCR). Spontaneous beating rate in atrial cardiomyocytes was detected with light microscope.</p><p><b>RESULTS</b>EGFP expression was seen in transfected atrial cardiomyocytes 24 to 48 hours after transfection and the spontaneous beating rate was significantly increased than that in non-transfected atrial cardiomyocytes [(180 +/- 11) bpm vs (140 +/- 14) bpm, P < 0.05]. Heart rate was significantly increased 24 hours post recombinant plasmids pIRES2-EGFP-HCN2 injection compared to saline injection in canines with SSS [(150 +/- 13) bpm vs (105 +/- 17) bpm, P < 0.05]. Green fluorescence was also detected in frozen SA tissue sections of canines injected with recombinant plasmids pIRES2-EGFP-HCN2 and the production amplified by RT-PCR was about 300 bp which is consistent with mHCN2 gene fragment.</p><p><b>CONCLUSION</b>The recombinant eukaryotic expression plasmid pIRES2-EGFP-HCN2 can improve pacing function in atrial myocytes and in canine model of SSS.</p>
Subject(s)
Animals , Dogs , Disease Models, Animal , Gene Expression , Gene Transfer Techniques , Genetic Therapy , Genetic Vectors , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels , In Vitro Techniques , Ion Channels , Genetics , Myocytes, Cardiac , Metabolism , Plasmids , Sick Sinus Syndrome , TherapeuticsABSTRACT
Objective To investigate the effect of neutral amino acid on preventing Parkinson disease.Methods Mice were injected with L-Valine,L-Pheylalanine,D-Valine or L-Lysine before or after paraquat administration,by which prakinsonian mouse model was constructed.The paraquat immunoreactivity was observed within nigral cell bodies.Then neurodegeneration and ?-synuclein aggregation were observed by immunohistochemistry and Western blot.Results Paraquat immunoreactivity was abolished by the administration of L-Valine,L-Pheylalanine before paraquat exposure.Pre-treatment with these two amino acids also protected the paraquat-induced loss of nigrostriatal dopaminergic cells and formation of thioflavine S-positive aggregates.In contrast, paraquat-induced toxicity was unaffected if animals were injected with these two amino acids after paraquat exposure or pre-treated with D-Valine or L-Lysine.Conclusions L-type neutral amino acids such as L Valine and L-Pheylalanine can prevent paraquat-induced neurodegeneration and a synuclein pathology through a competitive inhibition mechanism with stereospecificity in the central nervous system (CNS).Neutral amino acid could protect the dopaminergic neuron in substantia nigra and may prevent Parkinson disease.
