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Titolo:
PARASYMPATHETIC CONTROL OF CYCLE LENGTH DEPENDENCE OF ENDOCARDIAL VENTRICULAR REPOLARIZATION IN THE INTACT FELINE HEART DURING STEADY-STATECONDITIONS
Autore:
MALFATTO G; ZAZA A; SCHWARTZ PJ;
Indirizzi:
UNIV MILAN,VIA FRANCESCO SFORZA 35 I-20122 MILAN ITALY UNIV PAVIA,IST CLIN MED 2 I-27100 PAVIA ITALY UNIV PAVIA,DIPARTIMENTO FISIOL & BIOCHIM GEN I-27100 PAVIA ITALY UNIV PAVIA,DIPARTIMENTO MED I-27100 PAVIA ITALY
Titolo Testata:
Cardiovascular Research
fascicolo: 5, volume: 27, anno: 1993,
pagine: 823 - 827
SICI:
0008-6363(1993)27:5<823:PCOCLD>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
CARDIAC PURKINJE-FIBERS; ACTION-POTENTIAL DURATION; MYOCARDIAL-INFARCTION; CONSCIOUS DOGS; BAROREFLEX SENSITIVITY; ADRENERGIC MODULATION; VAGAL-STIMULATION; SUDDEN-DEATH; AUTOMATICITY; ACETYLCHOLINE;
Keywords:
VENTRICULAR REPOLARIZATION; MONOPHASIC ACTION POTENTIALS; AUTONOMIC NERVOUS SYSTEM; SYMPATHETIC-PARASYMPATHETIC INTERACTION; MUSCARINIC STIMULATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
42
Recensione:
Indirizzi per estratti:
Citazione:
G. Malfatto et al., "PARASYMPATHETIC CONTROL OF CYCLE LENGTH DEPENDENCE OF ENDOCARDIAL VENTRICULAR REPOLARIZATION IN THE INTACT FELINE HEART DURING STEADY-STATECONDITIONS", Cardiovascular Research, 27(5), 1993, pp. 823-827

Abstract

Objective: Parasympathetic modulation of the rate dependence of ventricular repolarisation in vivo during steady state conditions was investigated by analysing the effects of removing vagal activity in three groups of anaesthetised cats. Methods: Bilateral vagotomy was performedwhile different levels of background sympathetic tone were present inthe control periods of each group: in group 1 (n=6), cardiac sympathetic nerves were intact; in group 2 (n=7), bilateral stellate ganglionectomy was performed; and in group 3 (n=7), beta adrenergic blockade (propranolol, 0.5 mg.kg-1) was performed after stellate ganglionectomy. The duration of a left ventricular endocardial monophasic action potential (APD) was measured during atrial pacing at 7-10 cycle lengths (CL). The APD/CL relation was fitted to a hyperbolic function: APD=CL/[(aXCL)+b]. Two parameters were considered: APD(max) (1/a, ie, APD extrapolated at infinite cycle length, a rate-independent measure of APD) and CL50 (bXAPD(max), ie, the cycle length at which 50% of APD(max) is reached). Results: In control conditions, APD(max) and CL50 were longerin groups 2 and 3, when cardiac sympathetic effects were reduced or absent. Vagotomy reduced APD(max) and CL50 similarly in groups 1 and 2 (APD(max), -24% and -18%; CL50, -36% and -27%) (p<0.05 v control). In group 3, vagotomy did not affect APD(max) and CL50. Conclusions: No direct parasympathetic influence on the rate dependence of endocardial ventricular repolarisation was observed. The vagal modulation of sympathetic effects may take place either through vago-sympathetic reflexes or via the antagonism of circulating catecholamines distal to the betareceptor.

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Documento generato il 31/03/20 alle ore 10:28:39