Effects of ageing on regional differences in the contractile responses to acetylcholine and neurokinin A in rabbit airway.
1. Experiments were designed to study the effects of ageing on muscarine and NK2 receptor mechanisms in the three different regions of rabbit airway. 2. The pD2 value of acetylcholine changed with age in three different regions while that of carbamylcholine, which is resistant to acetylcholinesterase, did not. 3. The pD2 values of neurokinin A and the activity of protease, a degradative enzyme, changed with age. However, by the pretreatment with phosphoramidon, a protease inhibitor, the regional difference and age related change of the pD2 value of neurokinin A disappeared. 4. In conclusion, the observations about age related changes and regional differences of pD2 value of acetylcholine and neurokinin A were due to the difference of their degradative enzyme activities.
Department of Chemical Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
N
N
Funayama
M
M
Shinkai
S
S
Ebisawa
T
T
Abe
I
I
Takayanagi
D000109:Acetylcholine / Q000494:pharmacology*; D000375:Aging / Q000502:physiology*; D000818:Animals; D001980:Bronchi / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D015288:Neurokinin A / Q000494:pharmacology*; D011817:Rabbits; D014132:Trachea / Q000502:physiology*
D015288:Neurokinin A; D000109:Acetylcholine