Limitation of infarct size with preconditioning and calcium antagonist (diltiazem): difference in 99mTc-PYP uptake in the myocardium.
Ischemic cell injury and the uptake mechanism of 99mTc-PYP (Pyrophosphate) were studied with preconditioning and calcium antagonist.


METHODS
The coronary artery of an adult mongrel dog was clamped for 1 hour, followed by reperfusion and 99mTc-PYP injection. A control group (group C, n = 8), a group in which continuous drip infusion of diltiazem (10 mg/kg) (group D, n = 7), and a group preconditioned by six 5-minute clampings and perfusions before occlusion (group P, n = 6) were compared.


RESULTS
Wall motion was fully recovered in group D but not in group P after 2 hours of reperfusion. The 99mTc-PYP uptake ratio showed a significant (p < 0.05) reduction in group D (11.5 : 3.6 compared with group C), but not in group P (11.5 : 9.1, p = 0.25). The infarct area was 1.2 +/- 0.6% of the left ventricle in group D, 1.3 +/- 0.4 in group P, and 6.4 +/- 1.0 in group C (p < 0.01 in groups D and P vs. group C).


CONCLUSIONS
These findings suggest that preconditioning does not alleviate stunning, but it improves cell injury in spite of high uptake of 99mTc-PYP. Diltiazem protects from both stunning and cell injury, suggesting a different mechanism of myocardial protection from that of preconditioning.
Okuda
K
K
Department of Internal Medicine, Kyoto University Hospital, Japan.
Nohara
R
R
Ogino
M
M
Tamaki
N
N
Konishi
J
J
Fujita
M
M
Sasayama
S
S
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D003326:Coronary Circulation / Q000187:drug effects; D004110:Diltiazem / Q000494:pharmacology*; D004285:Dogs; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D011877:Radionuclide Imaging; D016698:Technetium Tc 99m Pyrophosphate / Q000493:pharmacokinetics*
D002121:Calcium Channel Blockers; D016698:Technetium Tc 99m Pyrophosphate; D004110:Diltiazem