Separate effects of ischemia, hypoxia, and contractility on thallium-201 kinetics in rabbit myocardium

Journal Article · Wed Jan 01 04:00:00 EST 1986 · J. Nucl. Med.; (United States)

OSTI ID:5684594

Leppo, J A; Macneil, P B; Moring, A F; Apstein, C S

The effects of hypoxia and ischemia, as well as altered contractility, on thallium-201 (/sup 201/TI) 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 /sup 201/TI kinetics were adequately described utilizing a bi-exponential model having a fast and slow component. Only ischemic hearts had significantly lower rate constants for /sup 201/TI uptake and clearance than normal hearts (p less than 0.001). The mean (+/- s.d.) myocardial uptake and clearance rates for /sup 201/TI (%/min) varied between 4.86 +/- 0.87 and 7.18 +/- 1.45 for the remaining groups of hearts. Therefore, myocardial /sup 201/TI 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 /sup 201/TI uptake in impaired or hypercontractile cells, receiving normal flow, may not represent normal cellular function.

• Research Organization: Univ. School of Medicine, MA
• OSTI ID: 5684594
• Journal Information: J. Nucl. Med.; (United States), Journal Name: J. Nucl. Med.; (United States) Vol. 1; ISSN JNMEA
• Country of Publication: United States
• Language: English

Related Subjects

560172* -- Radiation Effects-- Nuclide Kinetics & Toxicology-- Animals-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
ANOXIA
BETA DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BODY
CARDIOVASCULAR DISEASES
CARDIOVASCULAR SYSTEM
CLEARANCE
DAYS LIVING RADIOISOTOPES
DISEASES
ELECTRON CAPTURE RADIOISOTOPES
ELEMENTS
HEART
HEAVY NUCLEI
ISCHEMIA
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
MAMMALS
MUSCLES
MYOCARDIUM
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ORGANS
OXYGEN
RABBITS
RADIOISOTOPES
RADIONUCLIDE KINETICS
SECONDS LIVING RADIOISOTOPES
THALLIUM 201
THALLIUM ISOTOPES
UPTAKE
VASCULAR DISEASES
VERTEBRATES