PROTON MODULATIONS ON THE IONIC CURRENTS IN RABBIT ATRIO-VENTRICULAR NODAL CELLS

Modulations of changing the extracellular pH on the electrophysiological activity of isolated rabbit atrio-ventricular (AV) nodal cells were investigated using the two microelectrode voltage-clamp technique. Increasing pH from 7.4 to 9.5 enhanced spontaneous activity. The action potential amplitude and the maximum rate of depolarization were decreased. The action potential duration at 50% repolarization and the cycle length were shortened. The maximum diastolic potential was hyperpolarized. The pH elevation increased the maximum conductances for both the slow inward current and the delayed outward current systems. In contrast, a decline of pH from 7.4 to 5.5 inhibited the activity and the ionic currents. The effects on the action potential parameters were reversed. However, both acidification and alkalinization failed to affect the gating kinetics of the channels. These results suggest that H⁺ would modulate the electrical activity of the AV nodal cells, due not to an alteration of the membrane surface charge, but to a direct protonation of the ionic channels

USE-DEPENDENT BLOCK AND RECOVERY OF NA⁺ CHANNELS BY CLASS IC ANTIARRHYTHMIC DRUGS (FLECAINIDE AND ETHACIZIN) IN CANINE VENTRICULAR MUSCLE

Electrophysiological effects of flecainide and ethacizin (class Ic antiarrhythmic drugs) were examined using conventional microelectrode techniques. Flecainide significantly depressed the maximum rate of depolarization (⩒max) at 3x10⁻⁶M, and depolarized the resting potential (RP) at 10⁻⁵M, in a concentration-dependent manner. Ethacizin depressed ⩒max at 10⁻⁶M, and depolarized RP at 10⁻⁵M, significantly. However, both drugs did not affect the effective refractory period (ERP) nor the action potential duration (75% repolarization, APD₇₅). Both also had no effect on the action potential amplitude (APA). On the other hand, the drugs caused a use (or rate)-dependent block of ⩒max, and their time constants of onset of inhibition (at 3 Hz) were slow ; 6.3±1.2　msec (n=10) in the presence of flecainide (10⁻⁵M), and 6.0±1.6 msec (n=6) in the presence of ethacizin (10⁻⁵M). The time constants of the recovery were also so late : 12.2±2.5 sec (n=3) for flecainide (10⁻⁵M), and 27.1±13.3 sec (n=3) for ethacizin (2x10⁻⁶M), These results indicate that both antiarrhythmic drugs, flecainide and ethacizin, have no effect on APD₇₅ and ERP, but possess the characteristics for very slow kinetics of the use-dependent block and the recovery for fast Na⁺ channels of cardiac muscles. Ethacizin produces slower kinetics for the Na⁺ channels than flecainide

Formation of Flower-Like Crystals of Tris(8-hydroxyquinoline)aluminum from 8-Hydroxyquinoline on Anodic Porous Alumina

The treatment of anodic porous alumina (APA) plates in heated water containing 8-hydroxyquinoline (HQ) produces crystalline tris(8-hydroxyquinoline)aluminum (Alq3) microbelts about 5–10 μm wide and 5–20 μm long. These microbelts were found to aggregate to form flower-like structures on the surface. X-ray diffraction studies indicated that the Alq3 microbelts are composed of an α-phase having a meridional structure. The Alq3 microbelts exhibited green photoluminescence with a peak at around 520 nm. Scanning electron microscope images and energy dispersive X-ray spectra showed that this reaction is induced at the APA surface by the reaction between the HQ and amorphous Al2O3 species

Mathematical analysis of pressure Poisson methods and projection methods involving pressure boundary conditions for incompressible viscous flows

13301甲第5498号博士(理学)金沢大学博士論文要旨Abstrac