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Developmental Changes in Modulation of Cardiac Repolarization by Sympathetic Stimulation: The Role of Beta‐ and Alpha‐Adrenergic Receptors
Author(s) -
CUA MARK,
SHVILKIN ALEXEI,
DANILO PETER,
ROSEN MICHAEL R.
Publication year - 1997
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.1997.tb00847.x
Subject(s) - medicine , stellate ganglion , qt interval , stimulation , endocrinology , sympathetic nervous system , adrenergic , heart rate , adrenergic receptor , cardiology , propranolol , tachycardia , receptor , blood pressure , alternative medicine , pathology
Sympathetic Modulation of Cardiac Repolarization. Introduction : Our goals were to study the role of development in determining the cardiac effects of sympathetic neural activation, and to identify the roles of α‐ and β‐adrenergic receptor‐mediated pathways in modulating the effects of sympathetic stimulation. Methods and Results : We compared responses of young and adult canine hearts in situ to right, left, and bilateral stellate ganglion stimulation. We focused on changes in heart rate, rhythm, QT interval, rate‐corrected QT interval (QT), and T wave amplitude. Right stellate stimulation (RSS) induced more pronounced sinus tachycardia in adult than young animals. Left stellate stimulation (LSS) Induced junctional tachycardia in adult more than young animals. In adults, LSS and RSS prolonged QT c (LSS > RSS). whereas 1‐week‐olds manifested QT c shortening with RSS. LSS also increased T wave amplitude, most markedly in adults. In all studies, bilateral stellate stimulation induced responses intermediate between those seen with RSS and LSS. β‐Adrenergic blockade (propranolol) aholished all responses to LSS in adult hearts, but α‐blockade (prazosin) attenuated only the LSS‐induced prolongation in QT c.Conclusion : In the postnatal modulation of cardiac rhythm, rate, and repolarization by the sympathetic nervous system, β‐adrenergic receptors play a major role at all ages, whereas α‐adrenergic receptors play a lesser role, which is manifested only in adults. Moreover, expression of junctional tachycardias, which are β‐adrenergically modulated, is seen only in the adults.