Carbachol-induced down-regulation of receptors for pancreatic secretagogues.
Pancreatic acini possess a high affinity class of cholinergic receptors and a low affinity class of cholinergic receptors. Carbachol occupation of high affinity cholinergic receptors produces a reduction in binding of [3H]N-methylscopolamine. First incubating acini with carbachol caused a complete loss of high affinity cholinergic receptors with no change in the number or affinity of low affinity cholinergic receptors. Carbachol occupation of low affinity cholinergic receptors appears to produce a reduction in binding of 125I-CCK-8 and 125I-[Tyr4]bombesin. Acini possess two classes of CCK receptors. One class has a high affinity for CCK-8; the other class has a low affinity for CCK-8. First incubating acini with carbachol caused a 60% decrease in the number of high affinity CCK receptors with no change in the number of low affinity receptors or the affinities of either class of receptors for CCK-8. Acini possess a single class of bombesin receptors and first incubating acini with carbachol caused a 40% decrease in the number of bombesin receptors with no change in their affinity for bombesin.
Vinayek
R
R
Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Md.
Murakami
M
M
Sharp
C
C
Jensen
R T
RT
Gardner
J D
JD
D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D015536:Down-Regulation / Q000187:drug effects*; D006168:Guinea Pigs; D008297:Male; D019832:N-Methylscopolamine; D010179:Pancreas / Q000737:chemistry*; D010276:Parasympatholytics; D018004:Receptors, Bombesin; D011949:Receptors, Cholecystokinin / Q000187:drug effects; D011976:Receptors, Muscarinic / Q000187:drug effects* / Q000502:physiology; D017981:Receptors, Neurotransmitter / Q000187:drug effects; D012602:Scopolamine Derivatives
D010276:Parasympatholytics; D018004:Receptors, Bombesin; D011949:Receptors, Cholecystokinin; D011976:Receptors, Muscarinic; D017981:Receptors, Neurotransmitter; D012602:Scopolamine Derivatives; D002217:Carbachol; D019832:N-Methylscopolamine