Studies on tachykinin (neurokinin) receptor coupled with inositol phospholipid hydrolysis and salivation in rat salivary glands.
3H-substance P binding to the membranes of rat salivary glands was studied. The Kd and Bmax values were found to be 0.34 nM and 141 fmole/mg protein respectively using established natural occurring tachykinins to displace the binding. The rank order of potency was identified as substance P > neurokinin A > neurokinin B. These natural occurring tachykinins stimulate inositol phospholipid hydrolysis in slices of rat salivary glands, and the rank order of potency was also substance P > neurokinin A > neurokinin B. When salivation was induced by natural occurring tachykinins and acetylcholine (via i.v. route) in anesthetized rats with doses eliciting equivalent salivating responses, atropine blocks acetylcholine- as well as neurokinin B-, but not substance P- or neurokinin A-induced salivation. Based on the results mentioned above, we make a tentative conclusion that multiple receptor subtypes of neurokinins may exist in rat salivary glands. The neurokinins B receptor subtype is likely located presynaptically in the cholinergic nerve endings, whereas substance P and/or neurokinin A receptor subtypes may exist in the glandular tissue. The salivation induced by these neurokinins is likely through the activation of receptors, which are coupled to phosphatidylinositol turnover pathway.
Wei
J W
JW
Institute of Neurosciences, National Yang-Ming Medical College, Taipei, Taiwan, R.O.C.
Lee
F C
FC
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001667:Binding, Competitive / Q000187:drug effects; D006868:Hydrolysis; D066298:In Vitro Techniques; D007700:Kinetics; D008566:Membranes / Q000378:metabolism; D010275:Parasympathetic Nervous System / Q000502:physiology; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018041:Receptors, Neurokinin-2; D017981:Receptors, Neurotransmitter / Q000187:drug effects*; D012469:Salivary Glands / Q000378:metabolism / Q000502:physiology*; D012472:Salivation / Q000502:physiology*; D013268:Stimulation, Chemical; D013373:Substance P / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D015320:Tachykinins / Q000494:pharmacology
D010716:Phosphatidylinositols; D018041:Receptors, Neurokinin-2; D017981:Receptors, Neurotransmitter; D015320:Tachykinins; D013373:Substance P; D001285:Atropine; C038073:substance P, Arg(1)-Pro(2)-Trp(7),(9)-LeuNH(2)(11)-; D000109:Acetylcholine