Modulation of rabbit sinoatrial node activation sequence by acetylcholine and isoproterenol investigated with optical mapping technique
Changes in the rabbit sinoatrial node (SAN) activation sequence with the cholinergic and adrenergic factors were studied. The correlation between the sinus rhythm rate and the leading pacemaker site shift was determined. The hypothesis concerning the cholinergic suppression of nodal cell excitabilit...
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Published in | Acta Physiologica Vol. 196; no. 4; pp. 385 - 394 |
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Main Authors | , , , |
Format | Journal Article |
Language | English Russian |
Published |
Oxford, UK
Oxford, UK : Blackwell Publishing Ltd
01.08.2009
Blackwell Publishing Ltd Wiley-Blackwell |
Subjects | |
Online Access | Get full text |
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Summary: | Changes in the rabbit sinoatrial node (SAN) activation sequence with the cholinergic and adrenergic factors were studied. The correlation between the sinus rhythm rate and the leading pacemaker site shift was determined. The hypothesis concerning the cholinergic suppression of nodal cell excitability as one of the mechanisms associated with pacemaker shift was tested. A high-resolution optical mapping technique was used to register beat-to-beat changes in the SAN activation pattern under the influence of the cholinergic and adrenergic factors. Acetylcholine (10 μ m) and strong intramural parasympathetic nerve stimulation caused a pacemaker shift as well as rhythmic slowing and the formation of an inexcitable region in the central part of SAN. In this region the generation of action potentials was suppressed. The slowing of the sinus rhythm (which exceeded 12.8 ± 3.1% of the rhythm control rate) always accompanied the pacemaker shift. Isoproterenol (10, 100 n m, 1 μ m) and sympathetic postganglionic nerve stimulation also evoked a pacemaker shift but without formation of an inexcitable zone. The acceleration of the sinus rhythm, which exceeded 10.5 ± 1.3% of the control rate of the rhythm, always accompanied the shift. Both cholinergic and adrenergic factors cause pacemaker shifts in the rabbit SAN. While modest changes in the sinus rhythm do not coincide with the pacemaker shift, greater changes always accompany the shift and may be caused by it, according to one hypothesis. The formation of an inexcitable zone at the place where the leading pacemaker is situated is one of the mechanisms associated with pacemaker shift. |
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Bibliography: | http://dx.doi.org/10.1111/j.1748-1716.2009.01963.x istex:AB59B0AA5F24A7671111BC45020D141CEDAE117B ark:/67375/WNG-NFQG44NK-6 ArticleID:APHA1963 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2 |
ISSN: | 1748-1708 1748-1716 |
DOI: | 10.1111/j.1748-1716.2009.01963.x |