Malecot, Claire O. published the artcileLow voltage-activated channels in rat pulmonary vein cardiomyocytes: coexistence of a non-selective cationic channel and of T-type Ca channels, Application of Dimethyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate, the main research area is pulmonary vein cardiomyocyte cationic channel Ttype Ca; Basic science research; Electrophysiology; Ion channels/membrane transport.
Abstract: In rat pulmonary vein (PV) cardiomyocytes (CM), norepinephrine (NE) induces an automatic activity consisting of bursts of slow action potentials which depend on Ca2+ (upstroke) and Na+ (inter-burst) channels. Our objective was to characterize low voltage-activated (LVA) currents in rat PVCM susceptible to trigger this activity. Whole-cell ICa (5 mM Ca2+) was recorded from – 100 mV with classical Na+- and K+-free solutions A fast LVA ICa (FLVA-ICa), present in â?56% of PVCM between â?- 50 to – 20 mV, was blocked by 10μM TTX and markedly increased by addition of NaCl (1 or 3 mM) or KCl (5 or 10 mM). Permeability ratios P’Ca/PNa and P’Ca/PK calculated for bi-ionic conditions were resp. 2.25 ± 0.51 and 1.88 ± 0.25, and not different from a value of 2. FLVA-ICa was increased by 10μM NE and 300 nM BayK8644, decreased by 5μM nifedipine but not blocked by ranolazine (10μM). NiCl2 (40μM) and TTA-A2 (10 or 100 nM) increased FLVA-ICa. Similar results were obtained in left atrial (LA) CM. Neither Ba2+ nor Sr2+ alone could permeate the FLVA channel or block Ca2+ influx but revealed a large slower activating and inactivating LVA Ca2+ current (SLVA-ICa), present in 10 out of 80 PVCM, absent in LACM, and partially inhibited by 100 nM TTA-A2. Therefore, the ionic channel underlying FLVA-ICa is likely a fast voltage-gated non-selective channel with a dihydropyridine binding site. SLVA-ICa might correspond to Ca2+ influx through Cav3.x channels and contribute to triggering NE-induced automatic activity in the PV myocardial sleeve.
Pfluegers Archiv published new progress about Calcium channels Role: BSU (Biological Study, Unclassified), BIOL (Biological Study). 21829-25-4 belongs to class pyridine-derivatives, name is Dimethyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate, and the molecular formula is C17H18N2O6, Application of Dimethyl 2,6-dimethyl-4-(2-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate.