An acute exercise-induced translocation of beta-adrenergic receptors in rat myocardium.
The effect of acute exercise (treadmill running) on rat myocardium beta-adrenergic receptors (beta-AR) was studied. beta-AR was identified in purified sarcolemmal membrane fractions and light vesicle fractions. In control hearts, the number of beta-AR was 21.25 +/- 2.25 and 20.89 +/- 2.89 fmol/mg protein (mean +/- SE) in sarcolemmal membranes and light vesicles, respectively. Immediately after a single bout of dynamic exercise, about 35% of beta-AR was transferred from light vesicles to sarcolemmal membranes (p less than 0.05); concomitantly, isoproterenol-stimulated adenylate cyclase activity also significantly increased in sarcolemmal membranes (p less than 0.05). These results suggest that acute exercise provokes the translocation of beta-AR from a presumably intracellular site (light vesicles) to functional membrane fractions (sarcolemmal membranes) in rat myocardium.
Izawa
T
T
Laboratory for Exercise and Applied Physiology, Tokyo College of Pharmacy.
Komabayashi
T
T
Suda
K
K
Kunisada
Y
Y
Shinoda
S
S
Tsuboi
M
M
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D006321:Heart / Q000502:physiology*; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D012508:Sarcolemma / Q000502:physiology
D011943:Receptors, Adrenergic, beta; D000262:Adenylyl Cyclases; D007545:Isoproterenol