Document Detail

Inverse agonist activities of beta-adrenoceptor antagonists in rat myocardium.
MedLine Citation:
PMID:  10433496     Owner:  NLM     Status:  MEDLINE    
1. Negative inotropic effects of several beta-adrenoceptor (betaAR) antagonists on electrically-stimulated right atria, left atria, right ventricles and left ventricular papillary muscles from reserpine-treated rats were used as a measure of their inverse agonist activities. 2. Beta1AR antagonists acebutolol, atenolol and metoprolol, beta2AR antagonist ICI-181,551 and nonselective betaAR antagonists alprenolol, nadolol, propranolol and timolol produced negative inotropic effects, which were most marked on the right atria. 3. The nonselective betaAR antagonist pindolol did not exhibit inverse agonist activity but inhibited the negative inotropic activities of ICI-118,551, atenolol and propranolol. 4. The negative inotropic effects of lidocaine, nifedipine and pentobarbitone were similar on all the four myocardial preparations. 5. The positive inotropic efficacy of salbutamol on right and left atria but not on right ventricles and papillary muscles was comparable to that of isoprenaline. The antagonist activity of ICI-118,551 against isoprenaline was greater on right atria than on other cardiac regions. 6. Beta1AR proteins were expressed in all regions of the heart but of beta2AR were primarily localized in the right atrium. 7. It is concluded that beta2AR play a greater role in right atria than in other cardiac regions and almost all betaAR antagonists behave as inverse agonists.
D R Varma; H Shen; X F Deng; K G Peri; S Chemtob; S Mulay
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  British journal of pharmacology     Volume:  127     ISSN:  0007-1188     ISO Abbreviation:  Br. J. Pharmacol.     Publication Date:  1999 Jun 
Date Detail:
Created Date:  1999-08-26     Completed Date:  1999-08-26     Revised Date:  2013-06-11    
Medline Journal Info:
Nlm Unique ID:  7502536     Medline TA:  Br J Pharmacol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  895-902     Citation Subset:  IM    
Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada.
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MeSH Terms
Adrenergic beta-Agonists / pharmacology*
Adrenergic beta-Antagonists / pharmacology*
Albuterol / pharmacology
Blotting, Western
Isoproterenol / pharmacology
Myocardial Contraction / drug effects*
Pindolol / pharmacology
Propanolamines / pharmacology*
Rats, Sprague-Dawley
Receptors, Adrenergic, beta-1 / physiology
Receptors, Adrenergic, beta-2 / physiology
Reg. No./Substance:
0/Adrenergic beta-Agonists; 0/Adrenergic beta-Antagonists; 0/Propanolamines; 0/Receptors, Adrenergic, beta-1; 0/Receptors, Adrenergic, beta-2; 13523-86-9/Pindolol; 18559-94-9/Albuterol; 72795-19-8/ICI 118551; 7683-59-2/Isoproterenol

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