Kinetics of a putative hypoxic tracer, 99mTc-HL91, in normoxic, hypoxic, ischemic, and stunned myocardium.

Abstract

UNLABELLED:

99mTc-4,9-diaza-3,3,10,10-tetramethyldodecan-2,11-dione dioxime (HL91) was developed as a putative hypoxic reagent. This study focused on the myocardial kinetics of 99mTc-HL91 in various oxygen levels and perfusion states.

METHODS:

The time-activity curve of 99mTc-HL91 was measured in isolated perfused rat heart after the bolus infusion.

RESULTS:

99mTc-HL91 was cleared quickly from normoxic hearts, and retention at 30 min after injection was 0.18 +/- 0.02 percentage injected dose per gram of wet weight (mean +/- SE; n = 6). When the concentration of oxygen bubbling through the perfusate was reduced from 100% to 50%, 20%, 5%, and 0%, retention of 99mTc-HL91 increased to 0.47 +/- 0.03 (n = 5), 0.48 +/- 0.03 (n = 5), 0.71 +/- 0.01 (n = 5), and 0.70 +/- 0.02 (n = 5), respectively (P < 0.05). Compartment analysis revealed that the trapping mechanism, which was dependent on tissue oxygen concentration, determined the retention rate. Although not retained in stunned myocardium (0.17 +/- 0.02, n = 5; P = not significant), 99mTc-HL91 was significantly retained when injected before ischemia (1.06 +/- 0.06, n = 5; P < 0.05).

CONCLUSION:

These results indicate that retention of 99mTc-HL91 correlates well with oxygen level in the perfusate, suggesting that the agent may be a useful marker of the severity of myocardial hypoxia.

• Authors: K Imahashi, K Morishita, H Kusuoka, Y Yamamichi, S Hasegawa, K Hashimoto, Y Shirakami, M Kato-Azuma, T Nishimura
• Journal: Journal of nuclear medicine : official publication, Society of Nuclear Medicine (J Nucl Med) Vol. 41 Issue 6 Pg. 1102-7 (Jun 2000) ISSN: 0161-5505 [Print] United States
• PMID: 10855642 (Publication Type: Journal Article)

Chemical References

• Organotechnetium Compounds
• Oximes
• technetium Tc 99m 4,9-diaza-3,3,10,10-tetramethyldodecan-2,11-dione dioxime

Topics

• Animals
• Heart (diagnostic imaging)
• Hypoxia (diagnostic imaging, metabolism)
• In Vitro Techniques
• Male
• Myocardial Ischemia (diagnostic imaging)
• Myocardial Stunning (diagnostic imaging)
• Myocardium (metabolism)
• Organotechnetium Compounds (pharmacokinetics)
• Oximes (pharmacokinetics)
• Oxygen Consumption
• Radionuclide Imaging
• Rats
• Rats, Sprague-Dawley