Cardiomyopathy, Hypertrophic ; diagnosis ; therapy ; Humans

Cardiomyopathy, Hypertrophic ; diagnosis ; therapy ; Humans

Cardiomyopathy, Dilated ; genetics ; Genotype ; Humans ; Mutation

Blood Pressure ; physiology ; Humans ; Peptidyl-Dipeptidase A

Adrenergic beta-Antagonists ; therapeutic use ; Genomics

Cardiovascular Diseases ; etiology ; Diet ; Glycemic Index ; Humans

Hydrochlorothiazide ; pharmacology ; Pharmacogenetics

OBJECTIVETo identify the electrophysiological properties of long-QT syndrome (LQTS) associated missense mutations in the outer mouth of the HERG potassium channel in vitro.

METHODSMutations V630A and N633S were constructed by Megaprimer PCR method and cRNA were produced by T7 RNA polymerase. The electrophysiological properties of the mutation were investigated in the Xenopus oocyte heterologous expression system.

RESULTSCoexpression of mutant and wild-type HERG subunits caused a dominant-negative effect, and the currents were significantly decreased. Compared with wild-type HERG channels, V630A and N633S mutations were related to decreased time constants for inactivation for V630A/WT and N633S/WT at all potentials, reduced slope conductance and the voltage dependence of steady-state inactivation was shifted to negative potentials for V630A/WT and N633S/WT.

CONCLUSIONPresent study shows that LQTS associated missense mutations located in the outer mouth of HERG cause a dominant-negative effect and alterations in steady-state voltage dependence of channel gating of heteromultimeric channels suggesting a reduction in expressional current might be one of the pathophysiologic mechanisms of LQTS.

Animals ; DNA Mutational Analysis ; ERG1 Potassium Channel ; Electrocardiography ; Ether-A-Go-Go Potassium Channels ; genetics ; Humans ; Long QT Syndrome ; genetics ; Mutation, Missense ; Oocytes ; Patch-Clamp Techniques ; RNA, Complementary ; Xenopus

Objective To establish high-performance liquid chromatography with electrochemical detector(HPLC-ECD) method for the determination for metanephrine and normetanephrine in 24 h urine, and provide a superior test for the diagnostic of pheochromocytomas over plasma/urine catecholamine.Methods MCX solid-phase cartridge was used for extraction of metanephrine and normetanephrine,HPLC-ECD was used for their measurements.The intra-assay CVs,interassay CVs and recoveries of metanephrine and normetanephrine were also calculated.104 hypertensive patients without pheochromocytomas and 5 pheochromocytomas patients were selected in this study.The concentrations of metanephrine and normetanephrine were compared with the plasma and 24h urinary catecholamines concentrations.Results The intra-assay CV,inter-assay CV and recovery of metanephrine were 5.9%, 7.5%,91.1% respectively;the intra-assay CV,inter-assay CV and recovery of normetanephrine were 6.3%,6.6%,88.5%,respectively.The MN,NMN,plasma CA and urine CA of all pheochromocytomas patients were positive.MN and NMN were negative in controls,while plasma CA and urine CA are false positive in 15 patients and 14 patients in controls,respectively.Conclusions The study establish a fast and accurate method for quantification of metanephrine and normetanephrine in 24 h urine by HPLC-ECD.These findings also prove that it is the best biochemical assays for pheochromocytomas at present.

Antihypertensive Agents/therapeutic use* ; China ; Humans ; Hypertension/drug therapy* ; Research