Document Detail

Different toxicological profiles for various beta-blocking agents on cardiac function in isolated rat hearts.
MedLine Citation:
PMID:  6502785     Owner:  NLM     Status:  MEDLINE    
Propranolol, timolol and sotalol were compared regarding their cardiotoxic properties in isolated, perfused and catecholamine depleted rat hearts. Catecholamine depletion was performed in order to exclude interference of the drugs with beta-adrenergic receptors. The results demonstrate that both in spontaneously beating and atrial- stimulated hearts propranolol (3 - 30 micrograms/ml) and timolol (30 - 300 micrograms/ml) induced a dose dependent decrease in myocardial contractility, stimulus formation and stimulus conduction. Lacking local anesthetic properties as evidenced by effects on coronary flow and threshold voltage in the heart it can be deduced that the negative inotropic effect and an impaired stimulus conduction due to timolol can neither attributed to beta-adrenoceptor antagonism nor membrane stabilising activity. In addition, both propranolol (5 micrograms/ml) and timolol (200 micrograms/ml) reduced myocardial contractility to the same extent in ventricular-paced hearts. Therefore, a direct myocardial depressive effect rather than an indirect effect due to a reduced heart rate must be responsible for the negative inotropy. The hydrophilic beta-blocker sotalol demonstrated a slight cardiodepressant activity either in the spontaneously beating and atrial-stimulated hearts (30 - 300 micrograms/ml) or ventricular-paced hearts (300 micrograms/ml). It is concluded that the toxicological profile of various beta-blocking drugs might be determined by an yet unknown pharmacological property apart from beta-adrenoceptor blockade or membrane stabilising activity. Furthermore, the degree of lipophilicity of the drug might be an important determinant for the cardiotoxic profile of this class of drugs.
D de Wildt; B Sangster; J Langemeijer; G de Groot
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Publication Detail:
Type:  Comparative Study; Journal Article    
Journal Detail:
Title:  Journal of toxicology. Clinical toxicology     Volume:  22     ISSN:  0731-3810     ISO Abbreviation:  J. Toxicol. Clin. Toxicol.     Publication Date:  1984  
Date Detail:
Created Date:  1985-01-03     Completed Date:  1985-01-03     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8213460     Medline TA:  J Toxicol Clin Toxicol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  115-32     Citation Subset:  AIM; IM    
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MeSH Terms
Coronary Circulation / drug effects
Depression, Chemical
Electric Stimulation
Heart Rate / drug effects
Myocardial Contraction / drug effects*
Propranolol / toxicity*
Rats, Inbred Strains
Sotalol / toxicity*
Time Factors
Timolol / toxicity*
Reg. No./Substance:
26839-75-8/Timolol; 3930-20-9/Sotalol; 525-66-6/Propranolol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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