Exercise does not increase cyclooxygenase-2 myocardial levels in young or senescent hearts.
Increased myocardial cyclooxygenase-2 (COX-2) activity is essential for late phase ischemic preconditioning (IPC). Currently unknown is whether cardioprotection elicited by exercise also involves elevated myocardial COX-2 activity. This investigation tested whether aerobic exercise elevates myocardial COX-2 protein content or enzyme activity in young and senescent male Fisher 344 rats assigned to sedentary or cardioprotective endurance exercise treatments (3 consecutive days of treadmill exercise, 60 min/day @ approximately 70% VO(2)max). Assay of cardiac COX-2 protein content, catalytic activity, and inducible nitric oxide synthase (iNOS) protein content reveal that exercise did not alter COX-2 activity (PGE(2), p = 0.866; PGF1alpha, p = 0.796) or protein levels (p = 0.397) within young or senescent hearts. In contrast, myocardial iNOS, an up-stream mediator of COX-2 expression, was over-expressed by an average of 37% in aged hearts (p = 0.005), though iNOS was not influenced by exercise. Findings reveal exercise does not elevate cardiac COX-2 activity and suggests that mechanisms responsible for cardioprotection differ between IPC and aerobic exercise.
Quindry
John C
JC
Department of Applied Physiology and Kinesiology, Center for Exercise Science, University of Florida, Gainesville, FL 32611, USA. jcq0001@auburn.edu
French
Joel
J
Hamilton
Karyn L
KL
Lee
Youngil
Y
Selsby
Josh
J
Powers
Scott
S
D000375:Aging; D000818:Animals; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D005080:Exercise Test; D006321:Heart; D019194:Ischemic Preconditioning / Q000379:methods; D008297:Male; D009206:Myocardium / Q000201:enzymology* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D010805:Physical Conditioning, Animal; D011458:Prostaglandins E / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
D011458:Prostaglandins E; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat