The first magnetic circular dichroism (MCD) spectra are reported for tetraphenyltetraacenaphthoporphyrin (TPTANP). The impact on the electronic structure of steric interactions between the fused acenaphthalene rings and the meso-tetraphenyl substituents is explored based on an analysis of the optical spectra of the Zn(II) complex (ZnTPTANP) and the free base dication species ([H4TPTANP]2+). In the case of ZnTPTANP, significant folding of the porphyrinoid ligand induces a highly unusual MCD-sign reversal providing the first direct spectroscopic evidence of ligand nonplanarity. Density functional theory (DFT) geometry optimizations for a wide range of Zn(II) porphyrinoids based on the B3LYP functional and TD-DFT calculations of the associated UV-visible absorption spectra are reported, allowing a complete assessment of the MCD data. TPTANP complexes are found to fall into a class of cyclic polyenes, termed as soft MCD chromophores by Michl (J. Pure Appl. Chem. 1980, 52, 1549.), since the signs of the Faraday A1 terms observed in the MCD spectrum are highly sensitive to slight structural changes. The origin of an unusually large red shift of the main B (or Soret) band of MTPTANP (the most red shifted ever reported for fused-ring-expanded metal porphines) and of similar red shifts observed in the spectra of other peripherally crowded porphyrinoid complexes is also explored and explained on this basis.

Background-Ventricular fibrillation (VF) leads to global ischemia of the heart. After 1 to 2 minutes of onset, the VF rate decreases and appears more organized. The objectives of this study were to determine the effects of no-flow global ischemia on nonlinear wave dynamics and establish the mechanism of ischemia-induced slowing of the VF rate. Methods and Results-Activation patterns of VF in the Langendorff-perfused rabbit heart were studied with the use of 2 protocols: (1) 15 minutes of no-flow global ischemia followed by reperfusion (nϭ7) and (2) decreased excitability induced by perfusion with 5 mol/L of tetrodotoxin (TTX) followed by washout (nϭ3). Video imaging (Ϸ7500 pixels per frame; 240 frames per second) with a voltage-sensitive dye, ECG, and signal processing (fast Fourier transform) were used for analysis. The dominant frequency of VF decreased from 13.5Ϯ1.3 during control to 9.3Ϯ1.4 Hz at 5 minutes of global ischemia (PϽ0.02). The dominant frequency decreased from 13.9Ϯ1.1 during control to 7.0Ϯ0.3 Hz at 2 minutes of TTX infusion (PϽ0.001). The rotation period of rotors on the epicardial surface (nϭ27) strongly correlated with the inverse dominant frequency of the corresponding episode of VF (R 2 ϭ0.93). The core area, measured for 27 transiently appearing rotors, was 5.3Ϯ0.7 mm 2 during control. A remarkable increase in core area was observed both during global ischemia (13.6Ϯ1.7 mm 2 ; PϽ0.001) and TTX perfusion (16.8Ϯ3.6 mm 2 ; PϽ0.001). Density of wave fronts decreased during both global ischemia (PϽ0.002) and TTX perfusion (PϽ0.002) compared with control. Conclusions-This study suggests that rotating spiral waves are most likely the underlying mechanism of VF and contribute to its frequency content. Ischemia-induced decrease in the VF rate results from an increase in the rotation period of spiral waves that occurs secondary to an increase in their core area. Remarkably, similar findings in the TTX protocol suggest that reduced excitability during ischemia is an important underlying mechanism for the changes seen.

Drug-induced polymorphic ventricular arrhythmias may result from beat to beat changes in wave propagation patterns initiated by EADs or EAD-induced nonstationary reentrant activity. In contrast, burst pacing-induced polymorphic tachycardia in the presence or absence of drugs is the result of nonstationary reentrant activity.

The design and synthesis of a novel type of bisphthalocyanines, anti-[2.2](1,4)phthalocyaninophanes, were reported. The phthalocyanine dimer exhibited significantly split and red-shifted absorption in the near-IR region and maintained the fluorescence properties of phthalocyanines. The origin of the electronic communication between the two phthalocyanines was rationalized on the basis of the MO model analysis.

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The electronic excited states of a meso-meso beta-beta doubly linked bis-porphyrin are comprehensively investigated by measuring its circular dichroism (CD) and magnetic circular dichroism (MCD) spectra. The observed spectroscopic properties are rationalized by DFT calculations. The frontier molecular orbitals (MOs) are constructed by the linear combinations of the constituent monomers' four MOs. Comparison of a theoretical CD spectrum based on time-dependent DFT (TDDFT) with the experimental spectra resulted in the assignment of the helical conformation of the dimer. This assignment is contrary to the previous assignment based on the point-dipole approximation (exciton coupling theory).

The conventional L type Ca2+ channel current (ICa.L) was measured in single atrial and ventricular myocytes, with a new whole-cell recording technique using an ionophore, nystatin. The membrane of a cell-attached patch was gradually permeabilized by nystatin (100-200 micrograms/ml), added to the pipette solution, within 2-5 min after formation of a G omega-seal. The electrical activity of the cells was measured through the pipette. ICa.L, measured with the nystatin-whole cell recording technique, did not exhibit the so-called "run-down" phenomenon for up to 90 min. The response of ICa.L to isoprenaline was also well preserved during the measurement. The half maximal concentration for the isoprenaline-induced increase of ICa.L was 8.2 x 10(-9) M, which is a much smaller value than that reported previously. Thus, the nystatin-whole cell clamp recording is a useful technique to measure membrane currents of cardiac myocytes with preserving the physiological intracellular milieu.