Decrease in rat cardiac beta sub 1 - and beta sub 2 - adrenoceptors by training and endurance exercise

Journal Article · Sun Dec 31 23:00:00 EST 1989 · Life Sciences; (USA)

DOI:https://doi.org/10.1016/0024-3205(90)90051-R· OSTI ID:6532952

Werle, E O; Strobel, G; Weicker, H ^[1]

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1. Univ. of Heidelberg (West Germany)

The cardiac {beta}-adrenoceptor adaptation to physical activity was investigated in rats which were subjected to a six-week endurance swimming training (ET; n=7) and a training of high intensity (MT; n=7). In addition, the effect of a single bout of endurance exercise without preceding training (EE; n=7) was evaluated. These groups were compared with a sedentary control group (C; n=9). Beta-adrenergic receptors in rat myocardial membranes were labelled using the high affinity antagonist radioligand (-){sup 125}iodocyanopindolol (ICYP). Computer modelling techniques provided estimates of the maximal binding capacity (B{sub max}) and the dissociation constants (K{sub D}). Tissue was constantly kept at temperatures of {le}4{degrees}C and incubated at 4{degrees}C for 18 h in buffer containing 100 {mu}M GTP so as to prevent masking of {beta}-adrenoceptors by endogenous norepinephrine. In comparison with the C group computerized coanalyses of saturation binding data of ET, MT, and EE revealed a 13.0%, 25.5%, and 16.6% decrease in B{sub max}, respectively, without significantly differing K{sub D} values. We provide the first evidence that acute exercise lowers the sarcolemmal {beta}-adrenoceptor number in the rat heart. In the competition radioligand binding, CGP20712A and ICI118.551 were employed as subtype-selective antagonists of {beta}{sub 1}- and {beta}{sub 2}-adrenoceptors, respectively, to determine the relative proportions of the receptor subtypes.

• OSTI ID: 6532952
• Journal Information: Life Sciences; (USA), Journal Name: Life Sciences; (USA) Vol. 46:1; ISSN 0024-3205; ISSN LIFSA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BODY
CARDIOVASCULAR SYSTEM
CELL CONSTITUENTS
CELL MEMBRANES
COMPUTERIZED SIMULATION
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
EXERCISE
HEART
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
MAMMALS
MEMBRANE PROTEINS
MEMBRANES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SIMULATION
SYMPATHOMIMETICS
TRACER TECHNIQUES
VERTEBRATES