Density and functioning of human lymphocytic beta-adrenergic receptors during prolonged physical exercise.
In order to study the regulation of beta-adrenergic receptor number and function in response to prolonged physical effort, lymphocytic beta-adrenoceptor density (determined by (-)[125I]iodocyanopindolol binding), lymphocytic basal and isoproterenol-stimulated cyclic AMP (cAMP) production and concentrations of plasma catecholamines were measured before and during 3 h running exercise in eight healthy volunteers. A significant (P less than 0.01) increase of the lymphocytic beta-adrenoceptor density from 45 +/- 4 to 81 +/- 9 fmol mg-1 protein (mean +/- SEM) took place during the first hour of exercise. As the exercise was continued for up to 2.1-3 h, the receptor densities did not change significantly any more and remained elevated (72 +/- 9 fmol mg-1 protein) in comparison to the resting levels (P less than 0.02). The isoproterenol-stimulated cAMP production of the lymphocytes increased during the first hour of running from 190 +/- 36 to 269 +/- 56 pmol mg-1 protein (P less than 0.01) and returned to the resting level at the end of the exercise (182 +/- 38 pmol mg-1 protein). The mean levels of plasma catecholamines increased approximately sixfold during the first hour of exercise and remained elevated until the end of the running. This study demonstrates that the beta-adrenergic receptor system is activated in lymphocytes during prolonged aerobic physical exercise. This activated state becomes, however, attenuated within 2-3 h of exercise as indicated by a diminishing ability of beta-adrenoceptors to mediate catecholamine-induced cAMP production.
Mäki
T
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Department of Clinical Chemistry, University of Helsinki, Finland.
D000328:Adult; D000242:Cyclic AMP / Q000096:biosynthesis; D004837:Epinephrine / Q000097:blood; D015444:Exercise; D006801:Humans; D020120:Iodocyanopindolol; D007545:Isoproterenol / Q000494:pharmacology; D007773:Lactates / Q000097:blood; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D012420:Running; D013997:Time Factors
D007773:Lactates; D011943:Receptors, Adrenergic, beta; D020120:Iodocyanopindolol; D010869:Pindolol; D000242:Cyclic AMP; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine