THE DYNAMIC-RESPONSE OF THE BETA(2)-ADRENOCEPTOR AND ALPHA(2)-ADRENOCEPTOR IN HUMAN BLOOD-CELLS TO PROLONGED EXHAUSTING STRAIN, SLEEP AND ENERGY DEFICIENCY
P. Opstad et al., THE DYNAMIC-RESPONSE OF THE BETA(2)-ADRENOCEPTOR AND ALPHA(2)-ADRENOCEPTOR IN HUMAN BLOOD-CELLS TO PROLONGED EXHAUSTING STRAIN, SLEEP AND ENERGY DEFICIENCY, Biogenic amines, 10(4), 1994, pp. 329-344
Leucocyte beta2-receptors and platelet alpha2-receptors were studied d
uring a five days ranger training course with heavy physical activitie
s day and night, energy deficiency and almost without sleep. The beta2
-adrenoceptors on granulocytes and mononuclear cells decreased to a mi
nimum density and affinity after 2 and 4 days of activities respective
ly. For the rest of the course the beta2-receptors increased, however,
without reaching control values at the end of the course. A significa
nt decrease of about 15 % was found on day 3 in both platelet alpha2-r
eceptor density and affinity followed by an up-regulation to about 20%
above control levels on day 5. A significant correlation (r=-0.6 to-0
.8) between the beta2-receptor density and affinity, and the plasma ca
techolamines was recorded during the first 2-3 days, indicating a homo
logous down-regulation. The regeneration of receptors in spite of high
catecholamines reflects a predominance of heterologous up-regulation
during the second half of the course The results indicate that beta-ad
renergic receptor down-regulation contributes to attenuation of the ad
renergic responsiveness during the first 2-3 days of exhausting physic
al activities, but is not sufficient to account for the desensitizatio
n seen after longer periods of stress.