We studied the local anesthetic effects of the quaternary lidocaine analogues QX-314, QX-572, and QX-222, the tertiary amine lidocaine, its analogues tocainide, 6603, 6211, and the neutral local anesthetic benzocaine to determine if molecular charge of antiarrhythmic agents influences their local anesthetic effects on heart fibers. We used standard microelectrode techniques and canine cardiac Purkinje fibers to compare the effects of stimulation rate, drug concentration, and K+-induced changes in resting membrane potential on the reduction of fast inward sodium current using the maximum rate of rise of the action potential upstroke, Vmax, as an index of changes in peak sodium current. Use-dependent block, defined as a modulation of the reduction in Vmax by local anesthetics due to changes in the stimulation rate, was observed with the permanently charged analogues and was most prominent for agents existing predominantly in the charged form, but was absent for the neutral local anesthetic benzocaine. The development of use-dependent block during rapid stimulation preceded by prolonged periods of quiescence was an exponential process which became more rapid with increasing drug concentration. Recovery from use-dependent block during quiescence was an exponential process that was not influenced by similar drug concentration changes. All local anesthetics caused tonic block, defined as a drug-induced reduction of Vmax from control that attained a constant value at slow stimulation rates (cycle length range 15 seconds to 2 minutes) and was not changed by prolonged (up to 8 minutes) periods of quiescence. These findings suggest that the charged form of lidocaine and its analogues is responsible for use-dependent block of cardiac sodium channels.

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The microwave spectrum of CH3BF2 has been observed in the frequency range 12–33 kmc. The identifiable lines are explained in terms of a model consisting of a symmetric top (CH3) rotating with respect to an asymmetric framework (BF2) with the top axis coinciding with the (least) principal inertial axis of the molecule. The value of the barrier to internal rotation was determined to be 13.77±0.03 cal. Three moments of inertia were also obtained from the analysis: A = 10586.73 (BF2 group only), B = 8329.01, C = 4650.52 Mc. These are insufficient to determine the molecular structure, but are consistent with the structure reported from electron diffraction. Stark effect measurements yield a dipole moment of 1.67±0.02 D.

High resolution nuclear magnetic resonance spectra have been measured for the F19 resonance in some fluorine‐containing polymers. These data have shown that the F19 resonance frequency depends on the electronegativity of the other substituents on the carbon atom, in a manner similar to that found for small molecules. The resonance frequency also is dependent on substituents attached to adjacent carbons in a way not easily explained by inductive effects. It is hypothesized that these latter shifts may be due to direct potential interaction. The above generalizations, together with other supporting evidence, were utilized to assign a small peak in the spectrum of polyvinylidene fluoride to a head‐to‐head structure. This structure is present to the extent of 8–10%.

Amplitude-distance curves are different in the EUS and WUS; P decays-2.5-3.0 max as r and r in EUS and WUS, while for the maximum after 3.6 km/sec on-2-3 the vertical component (termed Lg) the decay rates are r and r. The EUS results are in general agreement with the literature and with the data presented by Nersesov and Rautian (1964) for events on the northern margin of tectonic regions in the Soviet Union suggesting that discrimination results in the EUS are relevant to NSS stations within the Soviet Union. Using these distance amplitude relations, network mean amplitudes at 1000 km were computed for L and P for earthquakes and explosions in the g max EUS and WUS and a separation of 0.6 magnitude units was observed thus forming a regional discriminant. The L is larger for earthquakes than for explosions. g This conclusion is somewhat uncertain in the WUS because of the large scatter in the explosion population. However, a reasonable explanation for this large scatter is that the small events at NTS are at such shallow depths in dry alluvium that the medium is weak, resulting in a low corner frequency. This decreases the ratio P /L since P contains comparatively more high frequency than L. The scatter probably would not be a problem in a true test ban situg ation since shots will be well buried to avoid surface collapse.