Norepinephrine turnover before and after interventions: A mathematical approach for these determinations in individual animals

Dykstra, Richard H.; Schmid, Phillip G.; Oda, Robert P.; Mayer, Howard E.

doi:10.1016/0160-5402(78)90060-8

Cited by 2 publications

(1 citation statement)

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“…Myocardial samples from the outer and inner thirds (epicardium and endocardium, respectively) were taken from the center of the phenol circle and from the untreated posterior left ventricle. Myocardial norepinephrine concentrations were measured using a fluorometric method (Dykstra et al, 1978). The same tissues were examined microscopically for catecholamine histofluorescence by the technique of Falck and Hillarp (Bjorlund et al, 1972).…”

Section: Norepinephrine Measurementsmentioning

confidence: 99%

Epicardial phenol interrupts refractory period responses to sympathetic but not vagal stimulation in canine left ventricular epicardium and endocardium.

Martins¹,

Zipes²

1980

Circulation Research

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SUMMARY We studied the effects of regional epicardial application of phenol on autonomic neural control of electrophysiological characteristics of the anterior left ventricle. In eight open-chest dogs, we applied a thin line of 88% phenol on the perimeter encircling a multipolar electrode and measured the effective refractory period (ERP) and recorded electrograms in phenol-encircled and untreated areas. Before phenol was applied, sympathetic nerve stimulation shortened ERP in all areas: percent change (A) 2 12. Phenol application to an area with a radius of 1-2 cm prevented ERP shortening in encircled epicardium during sympathetic stimulation, %A = 0.9 ± 0.8 (SEM), and attenuated ERP shortening in underlying endocardium, %\ = 2.5 ± 1.6, compared to ERP shortening in untreated areas, %d = 10 ± 1. A subsequent phenol application to an area with a radius of 2-3 cm prevented ERP shortening during sympathetic stimulation in both encircled epicardium and underlying endocardium. Phenol did not alter electrograms, activation times, or ERP shortening produced by norepinephrine infusion; these data suggest that electrophysiological characteristics of ventricular muscle encircled by phenol were unchanged apart from effects of withdrawal of sympathetic neural influence. To support these functional data, norepinephrine content measured in phenol-treated epicardium and endocardium of three dogs was 7 and 21%, respectively, of the norepinephrine content of untreated areas. In eight additional dogs, vagus nerve stimulation during norepinephrine infusion prolonged ERP by 3-5 msec both before and after phenol encircling an area with a radius of 2-3 cm. In these dogs, phenol did prevent ERP shortening during sympathetic nerve stimulation. We conclude that epicardial phenol interrupts sympathetic neural influences to both epicardial and endocardial sites without impairing responses either to intravenous norepinephrine or to vagus nerve stimulation. Circ Res 47: 33-40, 1980HISTOLOGICAL study of mammalian hearts has suggested that sympathetic efferent nerves approach the heart over the anterior great vessels, travel in the ventricular epicardium, and penetrate into the myocardium to innervate the endocardium (Hirsch, 1971). Vagal efferent nerves approach the heart over the posterior atria and may reach the ventricular myocardium via the ventricular septum as well as the epicardium (Hirsch, 1971). To provide functional confirmation of epicardial routes for sympathetic nerves, Szentivanyi et al. (1967), Randall et al. (1968), and Geis and Kaye (1968) interrupted nerves coursing immediately below the epiFrom the Krannert Institute of Cardiology, Department of Medicine, Indiana University School of Medicine, the Veterans Administration Hospital, Indianapolis, Indiana, and the University of Iowa, Iowa City, Iowa.This work was supported in part by the Herman C. Krannert Fund; by Grants HL-06308, HL-07182, HL-18795, and HL-14388 from the National Heart, Lung, and Blood Institute, National Institutes of Health, and by the American Heart Ass...

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Section: Norepinephrine Measurementsmentioning

confidence: 99%