Effects of aging on α2-adrenoceptor mechanisms in isolated guinea-pig tracheal preparations

The Contraction Mechanisms for Norepinephrine in Single Cells Prepared from Tracheal Smooth Muscles of Guinea Pig of Different Ages.

“…In the membrane preparation also, the KD value estimated from the Scatchard plots did not change with age, while the maximum binding sites (Borax) in creased with age from 6 to 40-weeks. These results are in good agreement with the find ings of Takayanagi et al (1991) who reported on the membrane fractions from guinea pig trachea (4). When the membrane fraction were used, about 50 guinea pigs were used in one binding experiment; the experiment was repeated several times to obtain the mean value, so that we used about 150 animals (4).…”

“…Takayanagi et al (2,3) recently reported the existence of a 2-adrenoceptors in the guinea pig trachea with which norepinephrine interacts and releases excitatory prostaglan dins, mainly prostaglandin F2a , to contract tracheal muscles. Norepinephrine potency re portedly decreases with age (4). In membrane fractions derived from the tracheal muscles of 6 and 40-week-old guinea pigs, the capacity of maximum binding sites of [3Hlp-amino clonidine was greater in the older animals, whereas the dissociation constant was un changed by age.…”

“…The amount of prostaglandin F2a released by norepinephrine and the con tractile response to it decreased with age. Takayanagi et al (1991) concluded from these results that the age-related decrease in the potency of norephinephrine is due to a reduc tion in the amount of excitable prostaglandin F2a released by norepinephrine and a reduc tion in the contractile response to prostaglan din F2a , but not to a change in the character istics of a2-adrenoceptors (4).To clarify the effects of aging on the con traction mechanism(s) for norepinephrine in …”

Age-related characteristics of epithelial-muscular interactions in the rat trachea

“…These ages were selected in accordance with the data on age-related characteristics of the respiratory system in rats [10]: These ages were selected in accordance with the data on age-related characteristics of the respiratory system in rats [10]:…”

“…At the same time, numerous data indicate that significant morphological and functional changes occur in the tracheobronchial system during ontogenesis [8,10,11]. At the same time, numerous data indicate that significant morphological and functional changes occur in the tracheobronchial system during ontogenesis [8,10,11].…”