Absence of correlations between plasma catecholamine levels and mononuclear leukocyte beta 2-adrenergic receptors in the elderly.
To assess the effects of aging on catecholamine plasma levels and mononuclear leukocyte (NML) beta 2-adrenergic receptors and on the possible relationships between these two parameters, we evaluated two groups of human subjects: 18 elderly volunteers (age 65-70 years) and 13 young volunteers (age 21-35 years). Norepinephrine plasma levels were significantly higher in the elderly subjects compared to the younger ones (P less than 0.05), whereas plasma epinephrine levels were not different. Also MNL beta 2-adrenoceptor density was significantly higher in elderly subjects (P less than 0.05). The binding dissociation constants were not significantly different. In young subjects there was a significant (P less than 0.02), inverse relationship between receptor densities and plasma norepinephrine levels; this relationship was not present in elderly persons. Our data suggest that the increase in beta 2-adrenoceptors may be due to a compensatory phenomenon, owing to the reduced beta-adrenergic sensitivity observed in the elderly subjects; moreover, the regulation of beta-adrenoceptors by plasma catecholamines seems to be altered by aging.
Pende
A
A
Cattedra di Patologia Medica R, DIMI, Università di Genova, Ospedale S Martino, Italy.
Musso
N R
NR
Vergassola
C
C
Ioverno
A
A
Galbariggi
G
G
Lotti
G
G
D000328:Adult; D000367:Age Factors; D000368:Aged; D004837:Epinephrine / Q000097:blood*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000737:chemistry*; D009638:Norepinephrine / Q000097:blood*; D011943:Receptors, Adrenergic, beta / Q000032:analysis*
D011943:Receptors, Adrenergic, beta; D009638:Norepinephrine; D004837:Epinephrine