Quantitative myocardial perfusion and coronary reserve in rats with 13N-ammonia and small animal PET: impact of anesthesia and pharmacologic stress agents.
The purpose of this study was to evaluate the effects of 2 anesthetic agents on myocardial perfusion and coronary reserve in rats under resting and stress conditions with small animal PET.


METHODS
Twenty-four rest/stress studies were performed in 6 rats. Each animal received all 4 possible combinations of anesthetic agents (propofol, isoflurane) and pharmacologic stress agents (dobutamine, adenosine) to increase myocardial perfusion. For each stress or rest study, a 10-min dynamic acquisition was performed in list mode with 185 MBq of (13)N-NH(3). Data analysis was performed according to a 3-compartment myocardial blood flow model. Pharmacologic stimulation by either dobutamine or adenosine was performed to increase myocardial perfusion.


RESULTS
The perfusion values (mean +/- SD) for the various experimental conditions were as follows: propofol/dobutamine, 7.8 +/- 2.4 mL/g/min (rest, 3.7 +/- 0.8 mL/g/min; mean +/- SD); isoflurane/dobutamine, 9.3 +/- 3.1 mL/g/min (rest, 4.3 +/- 1.0 mL/g/min); propofol/adenosine, 6.8 +/- 1.7 mL/g/min (rest, 3.2 +/- 0.4 mL/g/min); and isoflurane/adenosine, 5.2 +/- 1.3 mL/g/min (rest, 3.7 +/- 0.7 mL/g/min). All perfusion data showed a significant increase after pharmacologic stimulation relative to baseline (P < 0.05). The coronary reserve (mean +/- SD) measured by PET was slightly lower with the combination of isoflurane and adenosine (1.4 +/- 0.5) than with propofol and adenosine (2.1 +/- 0.5).


CONCLUSIONS
Noninvasive quantitative measurements of myocardial perfusion in small animals at rest and during stress are feasible using PET. Evaluation of the coronary reserve must take into account the initial state of the anesthetized animal. The coronary reserve could be measured with both anesthetic agents using either dobutamine or adenosine stimulation.
Croteau
Etienne
E
Département de médecine nucléaire et radiobiologie, Université de Sherbrooke, Sherbrooke, Québec J1H 5N4, Canada.
Bénard
François
F
Bentourkia
M'hamed
M
Rousseau
Jacques
J
Paquette
Michel
M
Lecomte
Roger
R
D000241:Adenosine / Q000008:administration & dosage*; D000641:Ammonia; D000777:Anesthetics / Q000008:administration & dosage; D000818:Animals; D016477:Artifacts; D003326:Coronary Circulation / Q000187:drug effects*; D004280:Dobutamine / Q000008:administration & dosage*; D005080:Exercise Test; D005240:Feasibility Studies; D006321:Heart / Q000000981:diagnostic imaging*; D007530:Isoflurane / Q000008:administration & dosage*; D008297:Male; D009590:Nitrogen Radioisotopes; D049268:Positron-Emission Tomography / Q000379:methods / Q000662:veterinary; D015742:Propofol / Q000008:administration & dosage*; D019275:Radiopharmaceuticals; D051381:Rats; D017207:Rats, Sprague-Dawley
D000777:Anesthetics; D009590:Nitrogen Radioisotopes; D019275:Radiopharmaceuticals; D004280:Dobutamine; D000641:Ammonia; D007530:Isoflurane; D000241:Adenosine; D015742:Propofol