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Results for “Neural Conduction”

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At least 1,117 records · Page 62Linked to original sources
PubMed1989

Effects of N-(2,6-dimethylphenyl)-8-pyrrolizidineacetamide hydrochloride hemihydrate on the ventriculo-atrial conductivity of accessory pathways.

The purpose of this study was to examine the effects of N-(2,6-dimethylphenyl)-8-pyrrolizidineacetamide hydrochloride hemihydrate (SUN 1165), a newly developed antiarrhythmic agent belonging to class Ic, on the ventriculoatrial (VA) conductivity of accessory pathways and paroxysmal supra-ventricular tachycardia (PSVT). Twelve patients with accessory pathways were examined by standard electrophysiologic technique before and after a single oral dose of SUN 1165 (100 mg). 1 h after administration, SUN 1165 blocked VA conduction of the accessory pathway in six of twelve patients and prevented the induction of PSVT in six of seven cases. In the cases in which VA block did not occur, the VA interval prolonged (from 178 +/- 7 to 190 +/- 11 ms, p less than 0.05), and the effective refractory period of VA conduction was also increased (from 273 +/- 10 to 318 +/- 15 ms. p less than 0.05). SUN 1165 also prolonged the conduction time in normal conduction systems (AH and HV intervals and QRS duration), but the degree of the prolongation was moderate and not dangerous. There was no adverse effect. These results indicate that SUN 1165 is a potent and safe antiarrhythmic agent, and useful for preventing or stopping PSVT by blocking or depressing VA conduction through accessory pathways.

Administration, Oral↗
PubMed2004

Conducting polymers grown in hydrogel scaffolds coated on neural prosthetic devices.

The conducting polymer polypyrrole (PPy) was electrochemically grown on hydrogel scaffolds deposited on the surface of microfabricated neural prosthetic devices. It is shown that the pyrrole monomer can be grown vertically through the hydrogel layer up to the surface without affecting the adjacent sites on the probes. The electrochemical properties of the conducting polymer-modified hydrogels were studied by impedance spectroscopy and cyclic voltammetry. It is also found that the conducting polymers could still be readily grown through the hydrogel after the microstructure is disrupted by freeze drying. Impedance measurements at the biologically important frequency of 1 kHz showed that the minimum impedance of this polymer-modified hydrogel was 7 kOmega. This is much lower than the minimum impedance of polypyrrole film ( approximately 100 kOmega).

Animals↗
PubMed1982

Electrophysiologic study demonstrating triple antegrade AV nodal pathways in patients with spontaneous and/or induced supraventricular tachycardia.

Ten patients are described with two discrete discontinuities in AV nodal conduction curves suggesting triple antegrade AV nodal pathways. This represents approximately 6% of patients seen in this laboratory with dual AV nodal pathways. Patients ranged in age from 18 to 63 (mean +/- SD, 48 +/- 15 years). Six of the 10 patients had organic heart disease and four did not. The effect of cycle length on triple pathways could be analyzed in 8 of 10 patients who had atrial extrastimulus testing at two or more cycle lengths. Three of these eight patients had triple pathways at all tested cycle lengths. Four patients had triple pathways only at shorter cycle lengths. One patient had triple pathways only at longer cycle lengths. Intact retrograde conduction was demonstrated in seven of ten patients, all of whom had atrial echoes (two patients) or inducible supraventricular tachycardia (SVT) (five patients). Echoes or SVT were induced on the slow pathway is all seven patients, but also on the intermediate pathway in three. However, sustained SVT usually reflected antegrade slow and retrograde fast pathway conduction. In conclusion, triple AV nodal pathways may be demonstrated in occasional patients during atrial extrastimulus testing. Thereby, functional longitudinal dissociation of the AV node is not limited to two pathways.

Adolescent↗
PubMed1985

Membrane potential and input resistance in alpha motoneurons of hindlimb extensors during isolated and clustered episodes of phasic events in REM sleep.

The function of motoneurons during the phasic events of REM sleep was investigated in cats. The membrane potential, synaptic activity, input resistance and rheobase were measured in hindlimb extensor motoneurons during periods of concentrated phasic events (Type II) in REM sleep in undrugged, minimally restrained cats. During Type II episodes in REM sleep, motoneurons depolarized 3 mV on the average, reduced in input resistance by 20%, and had distinct increases in spontaneous synaptic activity, as compared with periods of REM sleep between episodes (i.e. Type I). This constellation of properties is explained by increased frequencies of both unitary EPSPs and IPSPs in motoneurons. Myoclonic jerks in Type II episodes do not appear to arise because of a temporary withdrawal of the tonic motoneuron inhibition found in REM sleep. Instead, large increases in excitatory synaptic activity overcome the inhibition, giving rise to motoneuron discharges.

Animals↗