AN ANALYSIS OF SOME FACTORS INFLUENCINGα‐ADRENOCEPTOR FEED‐BACK AT THE SYMPATHETIC JUNCTION IN THE RAT HEART
1 The effects of the selective prejunctional α‐adrenoceptor antagonist, yohimbine, on the cardio‐acceleration responses to sympathetic stimulation were examined in the pithed rat. 2 Yohimbine reversed the inhibitory effects of the α‐adrenoceptor agonist, clonidine. on the stimulation‐induced tachyca...
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Published in | British journal of pharmacology Vol. 66; no. 1; pp. 55 - 63 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
Blackwell Publishing Ltd
01.05.1979
Nature Publishing Group |
Subjects | |
Online Access | Get full text |
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Summary: | 1
The effects of the selective prejunctional α‐adrenoceptor antagonist, yohimbine, on the cardio‐acceleration responses to sympathetic stimulation were examined in the pithed rat.
2
Yohimbine reversed the inhibitory effects of the α‐adrenoceptor agonist, clonidine. on the stimulation‐induced tachycardia.
3
Yohimbine failed to potentiate significantly responses to stimulation in the absence of clonidine when stimulation was applied at the optimal level for cardiac responses (C6‐T1).
4
When the pithing rod electrode was moved to T2‐T6, cardioaccelerator responses were smaller and yohimbine produced potentiation at frequencies of ≥ 1 Hz. This potentiation was prejunctional since responses to exogenous noradrenaline (NA) were not increased by yohimbine.
5
In the presence of cocaine, potentiation by yohimbine could be shown at the lower frequency of 0.1 Hz.
6
The possible physiological significance of a negative feed‐back effect of noradrenaline on cardiac sympathetic nerves is discussed. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0007-1188 1476-5381 |
DOI: | 10.1111/j.1476-5381.1979.tb16097.x |