Effect of ageing on alpha 1A-adrenoceptor mechanisms in rabbit isolated bronchial preparations.
Effect of aging on alpha 1A-adrenoceptor mechanisms in rabbit bronchial preparations was studied. The potency (pD2 value) of norepinephrine increased with age from 5 to 13 weeks and thereafter did not alter with age from 13 to 180 weeks. The affinity of norepinephrine (pKA value) and of a selective alpha 1A-adrenoceptor blocker, 5-methylurapidil (pA2 value) did not alter with age. Efficacy of norepinephrine was proportional to receptor reserve (pD2-pKA). These results suggest that age-related changes in alpha 1A-adrenoceptor mechanisms are due to changes in receptor reserve or total concentration of receptors, but not to changes in affinity of drugs to alpha 1A-adrenoceptors and in contraction mechanisms.
Takayanagi
I
I
Department of Chemical Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
Moriya
M
M
Koike
K
K
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology*; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*
D011942:Receptors, Adrenergic, alpha; D009638:Norepinephrine