The purpose of this study was to evaluate cyclooxygenase (COX)‐1 and ‐2 activation in response to an acute bout of resistance exercise (RE) in human skeletal muscle. Before, 4, and 24 hours after a bout of unilateral knee extensor RE (3 sets of 10 repetitions at 70% of maximum) muscle biopsies were taken from the vastus lateralis of seven young males (25±0.4 y). Biopsy samples were assayed for COX‐1 and COX‐2 activity (700200, Cayman Chemical). COX‐1 activity was not increased with RE (PRE: 5.0±1.0, 4 hrs: 6.5±1.1, 24 hrs: 7.7±1.9 nmol PGH2·g muscle−1·min−1) while COX‐2 activity was elevated at 24 (p<0.05) but not four hours after exercise (PRE: 4.5±1.1, 4 hrs: 5.8±1.1, 24 hrs: 8.9±1.4 nmol PGH2·g muscle−1·min−1). Prostaglandin (PG) production due to COX‐1 and COX‐2 was similar (COX‐1/COX‐2 ratio: 1.1±0.3) before RE. This ratio (0.8±0.3) decreased at 24 hours indicating a greater proportion of PG production from COX‐2. COX activity has been implicated as a necessary component of a RE‐induced increase in skeletal muscle protein synthesis. Muscle protein synthesis is elevated as early as 1–4 hours after RE. Thus our data suggest that an elevation in COX‐1 or COX‐2 activity may not be necessary for the RE‐induced increase in protein synthesis. Our findings also support the general consensus that COX‐2 is inducible and that COX‐2 enzyme activity is present in resting skeletal muscle.Funding: MWU Start‐Up Funds, and MWU College of Health Sciences

The purpose of this study was to evaluate the influence of acetaminophen (APAP) on collagen content in rat Achilles tendon. Ten‐week‐old male Wistar rats were given saline (SAL, n=8) or APAP (n=10; 200 mg·kg−1) once daily via oral gavage for 8 weeks. Tendon collagen content was determined by detection of the collagen specific amino acid hydroxyproline using HPLC. Following treatment, tendons, mm. gastrocnemius and soleus, fat pad, heart, liver, and femur and tibia bones were harvested. Tendon collagen content was greater (p<0.05) in the rats given APAP (SAL: 510.5±42.3; APAP: 663.4±38.0 μg collagen·mg tendon wet weight). Fat pad weight was greater (p<0.05) in the APAP group (SAL: 11.02±1.87; APAP: 15.83±1.36 g). Both femur and tibia weight [femur: (SAL: 867±19; APAP: 936±23 mg, tibia: (SAL: 644±22, APAP: 718±16 mg)] were greater (p<0.05) in the rats consuming APAP. M. soleus (SAL: 203±11; APAP: 240±9 mg) but not m. gastrocnemius (SAL: 2.73±0.05; APAP: 2.76±0.12 g) weight was greater (p<0.05) in the rats given APAP, whereas heart and liver weight was not different between groups. APAP appears to promote collagen deposition in tendon and has growth promoting affects on bone and skeletal muscle, however, the affect on skeletal muscle appears to be specific to the type I soleus muscle. The specific mechanisms of these effects require further study.MWU College of Health Sciences and MWU Office of Research and Sponsored Programs