Neurally induced digitalis arrhythmias and adrenoreceptors

Subbiah Sivam, S. D. Seth, U. Nayar, S. C. Manchanda

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Intracerebroventricular (i.c.v.) administration of ouabain to chloralose-anesthetized, vagotomized cats elicited a dose-related increase in blood pressure and heart rate followed by ventricular arrhythmias; these effects were attributable to a sympathoadrenal discharge triggered from the central nervous system. In presence of an effective vascular α-blockade with an i.v. α-blocker, the vasopressor response to i.c.v. ouabain was reversed to a vasodepressor one; this is reminiscent of the 'vasomotor reversal phenomenon of Dale'. On the other hand, in the precence of an effective β-blockade with an i.v. β-blocker the vasopressor response was augmented. The vascular response to i.c.v. ouabain is thus the net effect mediated by both α- and β2-receptors and the blockade of one unmasks the other. The pre-existing α-blockade prevented the appearance of arrhythmias after i.c.v. ouabain. This may have been due to the ability of the α-blocker to prevent the rise in BP, however, a direct antiarrhythmic affect on the heart may also have been involved. The pre-existing β-blockade failed to significantly affect the tachycardia and the incidence of arrhythmias. This suggests that adrenergic neurogenic arrhythmias differ from the arrhythmias induced by exogenously administered catecholamines, since the latter are completely antagonized by β-blockers whereas the former are less readily antagonized. Further, the ability of a β-blocker to inhibit the isoprenaline-induced tachycardia (as a test of β-blockade) may not accurately reflect the ability to antagonize the cardiac effects evoked by a strong and diffuse sympathetic stimulation. Furthermore, it appears that the blockade of cardiac β-receptors is not equivalent to surgical sympathetic denervation of the heart and that the arrhythmogenic stimuli originating in the central nervous system may travel to the heart through pathways resistant to conventionally employed antagonists such as β-blockers.

Original languageEnglish (US)
Pages (from-to)107-115
Number of pages9
JournalEuropean Journal of Pharmacology
Volume68
Issue number2
StatePublished - 1980
Externally publishedYes

Fingerprint

Digitalis
Cardiac Arrhythmias
Ouabain
Tachycardia
Blood Vessels
Central Nervous System
Chloralose
Sympathectomy
Isoproterenol
Adrenergic Agents
Catecholamines
Cats
Heart Rate
Blood Pressure
Incidence

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Pharmacology

Cite this

Sivam, S., Seth, S. D., Nayar, U., & Manchanda, S. C. (1980). Neurally induced digitalis arrhythmias and adrenoreceptors. European Journal of Pharmacology, 68(2), 107-115.

Neurally induced digitalis arrhythmias and adrenoreceptors. / Sivam, Subbiah; Seth, S. D.; Nayar, U.; Manchanda, S. C.

In: European Journal of Pharmacology, Vol. 68, No. 2, 1980, p. 107-115.

Research output: Contribution to journalArticle

Sivam, S, Seth, SD, Nayar, U & Manchanda, SC 1980, 'Neurally induced digitalis arrhythmias and adrenoreceptors', European Journal of Pharmacology, vol. 68, no. 2, pp. 107-115.
Sivam, Subbiah ; Seth, S. D. ; Nayar, U. ; Manchanda, S. C. / Neurally induced digitalis arrhythmias and adrenoreceptors. In: European Journal of Pharmacology. 1980 ; Vol. 68, No. 2. pp. 107-115.
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