Document Detail

Ricin depresses cardiac function in the rabbit heart.
MedLine Citation:
PMID:  8658515     Owner:  NLM     Status:  MEDLINE    
Ricin, at toxic glycoprotein from the castor bean, causes myocardial hemorrhage and a decrease in blood pressure. We studied the effects of ricin on myocardial function in the isolated rabbit heart. Rabbits were given 0.22 micrograms/kg of ricin i.v. and 48 hr later, the heart was isolated and retrogradely perfused through the aorta with Tyrode's solution. A latex balloon was inserted into the left ventricle and isovolumic left ventricular function curves were generated. Left ventricular developed pressure (LVDP), heart rate, coronary artery flow, left ventricular end diastolic pressure, myocardial oxygen consumption, oxygen extraction (a - vO2), and contractility (+dp/dt) were measured over a range of left ventricular volumes. Dose-response curves to isoproterenol (10(-9)-10(-8) M) and phenylephrine (10(-9)-10(-6) M) were also obtained. Compared to the control group, ricin pretreatment markedly decreased ventricular compliance (p < 0.01), diminished maximum left ventricular developed pressure (p < 0.05), and reduced maximal +dp/dt (p < 0.05). Myocardial oxygen consumption, heart rate, electrocardiographic PR, QRS, and QT intervals were not different in control and ricin treatment groups. Ricin did not significantly alter the inotropic or chronotropic responses to isoproterenol and phenylephrine. The results from the binding studies showed that ricin neither reduced beta-adrenergic receptor numbers nor altered the dissociation constant. thus, ricin reduced both systolic (LVDP and +dp/dt) and diastolic (compliance) left ventricular functions, perhaps due to increased vascular permeability, without altering responses to the alpha- and beta-adrenoceptor agonists phenylephrine and isoproterenol.
L Ma; C H Hsu; E Patterson; U Thadani; C P Robinson
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Toxicology and applied pharmacology     Volume:  138     ISSN:  0041-008X     ISO Abbreviation:  Toxicol. Appl. Pharmacol.     Publication Date:  1996 May 
Date Detail:
Created Date:  1996-07-26     Completed Date:  1996-07-26     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0416575     Medline TA:  Toxicol Appl Pharmacol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  72-6     Citation Subset:  IM    
Department of Medicine, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA.
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MeSH Terms
Adrenergic beta-Agonists / pharmacology
Adrenergic beta-Antagonists / pharmacology
Dihydroalprenolol / metabolism
Heart / drug effects*,  physiology
Isoproterenol / pharmacology
Myocardial Contraction / drug effects*
Myocardium / metabolism
Oxygen Consumption / drug effects
Propranolol / pharmacology
Receptors, Adrenergic, beta / drug effects,  metabolism
Ricin / toxicity*
Ventricular Function, Left / drug effects
Reg. No./Substance:
0/Adrenergic beta-Agonists; 0/Adrenergic beta-Antagonists; 0/Receptors, Adrenergic, beta; 525-66-6/Propranolol; 60106-89-0/Dihydroalprenolol; 7683-59-2/Isoproterenol; 9009-86-3/Ricin

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