Document Detail


Separate effects of ischemia, hypoxia, and contractility on thallium-201 kinetics in rabbit myocardium.
MedLine Citation:
PMID:  3941367     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effects of hypoxia and ischemia, as well as altered contractility, on thallium-201 (201TI) kinetics were evaluated in 42 isolated isovolumetrically contracting rabbit hearts. In Group A, three subgroups (n = 7 each) were studied that had either normal flow and oxygenation, hypoxia and normal flow, or ischemic flow and normal perfusate oxygen content. In Group B, three subgroups (n = 7 each) were studied and all hearts had normal flow but the contractile state was either enhanced with isoproterenol or impaired by hypocalcemia. A hemoglobin-free buffer perfusate was used in all experiments and multiple timed collections of arterial and coronary sinus effluent were used to model myocardial isotope activity during 30 min of constant uptake followed by 30 min of tracer clearance. During ischemia, hypoxia and hypocalcemia peak developed pressure and peak positive and negative dP/dt were all significantly reduced when compared to normal hemodynamic parameters (p less than 0.01). As expected, isoproterenol significantly elevated these parameters (p less than 0.04). Myocardial 201TI kinetics were adequately described utilizing a bi-exponential model having a fast and slow component. Only ischemic hearts had significantly lower rate constants for 201TI uptake and clearance than normal hearts (p less than 0.001). The mean (+/- s.d.) myocardial uptake and clearance rates for 201TI (%/min) varied between 4.86 +/- 0.87 and 7.18 +/- 1.45 for the remaining groups of hearts. Therefore, myocardial 201TI kinetics appear to be dominated by coronary flow and may not reflect marked alterations in the metabolic and contractile state. These data suggest that normal 201TI uptake in impaired or hypercontractile cells, receiving normal flow, may not represent normal cellular function.
Authors:
J A Leppo; P B Macneil; A F Moring; C S Apstein
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of nuclear medicine : official publication, Society of Nuclear Medicine     Volume:  27     ISSN:  0161-5505     ISO Abbreviation:  J. Nucl. Med.     Publication Date:  1986 Jan 
Date Detail:
Created Date:  1986-02-20     Completed Date:  1986-02-20     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0217410     Medline TA:  J Nucl Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  66-74     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Coronary Circulation
Coronary Disease / radionuclide imaging*
Heart / radionuclide imaging*
Kinetics
Male
Models, Cardiovascular
Myocardial Contraction*
Myocardium / metabolism
Oxygen / pharmacology*
Oxygen Consumption
Rabbits
Radioisotopes / diagnostic use*
Thallium / diagnostic use*,  metabolism
Time Factors
Grant Support
ID/Acronym/Agency:
HL23406/HL/NHLBI NIH HHS; HL29464/HL/NHLBI NIH HHS; HL31953/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Radioisotopes; 7440-28-0/Thallium; 7782-44-7/Oxygen

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


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