Meeting Abstract

P1.74  Jan. 4  Epinephrine Does Not Promote Cardiac Glycogen Depletion In Vitro In Rainbow Trout SORENSEN, Olav J.*; BATTIPROLU, Pavan K.; RODNICK, Kenneth J.; Idaho State University; Idaho State University; Idaho State University

During stress, including environmental hypoxia and elevated swimming activity, circulating epinephrine increases in fishes. In mammals, it is known that epinephrine promotes glycogenolysis and cardiac performance. However, the effect of adrenergic stimulation on cardiac glycogen metabolism in male and female rainbow trout has not been established. Therefore, we determined whether epinephrine stimulates glycogen depletion under highly oxygenated (PO2 = 640 mm Hg) conditions in contracting and non contracting ventricle strips from rainbow trout. METHODS: Uniform ventricles strips were cut from 10-12 month old males and females (n=5-10), and were either attached to isometric force transducers, stimulated electrically at 0.5 Hz or were incubated in Ringers (controls). Epinephrine (10 nm or 10 µM) was added to contracting and non contracting preparations for 60 min. Ventricle tissue was freeze clamped before(initial values) and at the end of experiments and stored at -80°C until glycogen assays were performed. RESULTS: Males had higher initial glycogen concentrations compared to females (20.03 ± 5.48 vs. 11.27 ± 3.56 mg/g tissue, P=0.0397). For both sexes, control and treated strips were not significantly different. CONCLUSION: While initial glycogen concentrations were higher in males, neither 1) incubations of cardiac tissue in glucose under oxygenated conditions nor 2) the addition of epinephrine, depletes cardiac glycogen in rainbow trout. Funded by NIH P20RR16454, NSF-Idaho EPSCoR EPS 0447689, and NSF IOB-517669.