Influence of beta-adrenoceptor blockade on the myocardial accumulation of fatty acid tracer and its intracellular metabolism in the heart after ischemia-reperfusion injury.
BACKGROUND
Increases in sympathetic nerve activity during ischemia may increase intracellular fatty acid (FA) accumulation via enhanced FA uptake and inhibition of beta-oxidation. Therefore, the beneficial effects of beta-adrenoceptor blockade on myocardial ischemic injury might result from the suppression of FA accumulation.


RESULTS
Carvedilol (1 mg/kg) or propranolol (1 mg/kg) was injected 10 min before 15-min occlusion of coronary artery in rats. Myocardial FA accumulation and intracellular metabolites of FA tracer were determined 3 days after reperfusion using (125)I-and (131)I-9-metylpentadecanoic acid (9MPA). Carvedilol significantly decreased 9MPA accumulation in both the ischemic region (IR) and non-IR, as compared with vehicle, and increased its clearance. However, the non-metabolized 9MPA fraction was not different between carvedilol- and vehicle-treated rats. Consequently, the amount of non-metabolized 9MPA in the myocardium was lower in rats treated with carvedilol than in those given vehicle. These effects of carvedilol were not different from those of propranolol.


CONCLUSIONS
Beta-adrenoceptor blockade did not affect a visual assessment of the autoradiographic image of 9MPA in hearts subjected to ischemia-reperfusion, but it accelerated the clearance of 9MPA in both the IR and non-IR. The administration of beta-blockade before ischemia could accelerate the recovery from ischemia-reperfusion injury by inhibiting myocardial FA accumulation before beta-oxidation.
Igarashi
Norio
N
Second Department of Internal Medicine, Faculty of Medicine, University of Toyama, Toyama 930-0194, Japan.
Nozawa
Takashi
T
Fujii
Nozomu
N
Suzuki
Takayuki
T
Matsuki
Akira
A
Nakadate
Teruo
T
Igawa
Akihiko
A
Inoue
Hiroshi
H
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001345:Autoradiography / Q000379:methods; D002227:Carbazoles / Q000494:pharmacology; D000077261:Carvedilol; D005227:Fatty Acids / Q000378:metabolism*; D007462:Iodobenzenes / Q000378:metabolism; D008297:Male; D017202:Myocardial Ischemia / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism*; D010084:Oxidation-Reduction; D011412:Propanolamines / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D015427:Reperfusion Injury / Q000378:metabolism*
D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; D005227:Fatty Acids; D007462:Iodobenzenes; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; C049338:iodofiltic acid; D000077261:Carvedilol; C067799:4-iodophenyl-9-methylpentadecanoic acid; D011433:Propranolol