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Titolo:
Effect of stimulating non-myelinated vagal axons on atrio-ventricular conduction and left ventricular function in anaesthetized rabbits
Autore:
Perez, MG; David, J;
Indirizzi:
Royal Free & Univ Coll Med Sch, Dept Physiol, London NW3 2PF, England Royal Free & Univ Coll Med Sch London England NW3 2PF n NW3 2PF, England Fac Med Sci, Havana, Cuba Fac Med Sci Havana CubaFac Med Sci, Havana, Cuba
Titolo Testata:
AUTONOMIC NEUROSCIENCE-BASIC & CLINICAL
fascicolo: 3, volume: 86, anno: 2001,
pagine: 183 - 191
SICI:
1566-0702(20010114)86:3<183:EOSNVA>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
GUINEA-PIG HEART; ANESTHETIZED CATS; NITRIC-OXIDE; NEURONS; NUCLEUS; RATS; CONTRACTILITY; PROJECTIONS; MOTONEURONS; MODULATION;
Keywords:
heart rate; A-V conduction; contractility; vagal nerve;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: David, J Royal Free & Univ Coll Med Sch, Dept Physiol, Royal Free Campus,Rowland Hill St, London NW3 2PF, England Royal Free & Univ Coll Med Sch Royal Free Campus,Rowland Hill St London England NW3 2PF
Citazione:
M.G. Perez e J. David, "Effect of stimulating non-myelinated vagal axons on atrio-ventricular conduction and left ventricular function in anaesthetized rabbits", AUTON NEURO, 86(3), 2001, pp. 183-191

Abstract

It has previously been demonstrated in several species that stimulation ofmyelinated vagal efferent fibres evokes slowing of heart rate and atrio-ventricular (A-V) conduction and a decreased ventricular contractility but recruitment of non-myelinated fibres did not further increase the response. Only in rabbits was a significant bradycardia evoked on recruiting non-myelinated fibres. However, if stimulating myelinated fibres produced a near maximal response, then effects of further activation of non-myelinated fibres may have been missed. Indeed, selective stimulation of non-myelinated fibres alone nov; has been shown to evoke a slowing of heart rate independent ofthe effects of myelinated fibres. In the present study we tested in rabbits whether selective stimuli are also capable of slowing A-V conduction and changing ventricular contractility. In rabbits pretreated with the beta (1)-adrenoceptor antagonist atenolol, EGG, arterial blood pressure, left ventricular pressure and dP/dt were recorded before and during stimulation of non-myelinated vagal efferent fibres using an anodal block technique (J. Physiol. 273 (1977) 539). R-R interval and A-V conduction times were computed off-line. Stimulation of non-myelinated vagal fibres increased R-R interval by 97.7+/-18.8 ms from a baseline of 315.3+/-7.7 ms, increased A-V conduction time by 9.9+/-1.1 ms from a baseline of 81.9+/-3.1 ms and decreased leftventricular dP/dt(max) by 2486+/-362 mmHg s(-1) from a baseline of 11 186+/-795 mmHg s(-1). When hearts were paced at a rate about 10% higher than normal, A-V conduction time still increased by 13.3+/-1.9 ms from a baseline of 104.3+/-3.6 ms and dP/dt(max) still fell by 2300+/-188 mmHg s(-1) from abaseline of 11200+/-777 mmHg s(-1). Ganglionic blockade with hexamethonium(15-20 mg kg(-1)) always abolished the evoked increases in A-V conduction time, whilst there was still an increase in R-R interval in seven of the 12animals tested. The data demonstrate that non-myelinated vagal efferent fibres can modulate chronotropic, dromotropic and inotropic actions on the heart. (C) 2001 Published by Elsevier Science B.V.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 29/03/20 alle ore 09:31:31