Differential affinities of AF-DX 116, atropine and pirenzepine for muscarinic receptors of guinea pig gastric fundus, atria and urinary bladder: might atropine distinguish among muscarinic receptor subtypes? 1990

M Del Tacca, and R Danesi, and C Blandizzi, and M C Bernardini
Institute of Pharmacology, School of Medicine and Dentistry, University of Pisa, Italy.

The pA2 values and the Schild plots of the antimuscarinic drugs AF-DX 116, atropine and pirenzepine for muscarinic receptors of isolated guinea pig gastric fundus (acid secretion) and atrial and urinary bladder preparations (contractile force) obtained from the same animals were calculated against bethanechol as the agonist. The antimuscarinic drugs concentration-dependently shifted the concentration-response curves to bethanechol to the right without any change in the maximum response. The analysis of data based on Schild plots was consistent with a simple competitive antagonism, since regression slopes did not differ significantly from unity. The pA2 values indicated a significantly higher affinity of AF-DX 116 and atropine for atrial muscarinic receptors with respect to those of the gastric mucosa or urinary bladder. By contrast, in the case of pirenzepine the pA2 values for the three tissues did not differ significantly. These results suggest that each examined tissue apparently contains homogeneous population of acetylcholine muscarinic (M2) receptors. The pA2 values found for AF-DX 116 and atropine suggest, however, that the putative M2 subtype of atrial muscarinic receptor differs from both those of the gastric fundus and those of the urinary bladder.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008297 Male Males
D009206 Myocardium The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow. Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010276 Parasympatholytics Agents that inhibit the actions of the parasympathetic nervous system. The major group of drugs used therapeutically for this purpose is the MUSCARINIC ANTAGONISTS. Antispasmodic,Antispasmodic Agent,Antispasmodic Drug,Antispasmodics,Parasympathetic-Blocking Agent,Parasympathetic-Blocking Agents,Parasympatholytic,Parasympatholytic Agent,Parasympatholytic Drug,Spasmolytic,Spasmolytics,Antispasmodic Agents,Antispasmodic Drugs,Antispasmodic Effect,Antispasmodic Effects,Parasympatholytic Agents,Parasympatholytic Drugs,Parasympatholytic Effect,Parasympatholytic Effects,Agent, Antispasmodic,Agent, Parasympathetic-Blocking,Agent, Parasympatholytic,Agents, Antispasmodic,Agents, Parasympathetic-Blocking,Agents, Parasympatholytic,Drug, Antispasmodic,Drug, Parasympatholytic,Drugs, Antispasmodic,Drugs, Parasympatholytic,Effect, Antispasmodic,Effect, Parasympatholytic,Effects, Antispasmodic,Effects, Parasympatholytic,Parasympathetic Blocking Agent,Parasympathetic Blocking Agents
D010890 Pirenzepine An antimuscarinic agent that inhibits gastric secretion at lower doses than are required to affect gastrointestinal motility, salivary, central nervous system, cardiovascular, ocular, and urinary function. It promotes the healing of duodenal ulcers and due to its cytoprotective action is beneficial in the prevention of duodenal ulcer recurrence. It also potentiates the effect of other antiulcer agents such as CIMETIDINE and RANITIDINE. It is generally well tolerated by patients. Gastrotsepin,Gastrozepin,L-S 519,LS-519,Piren-Basan,Pirenzepin,Pirenzepin Von Ct,Pirenzepin-Ratiopharm,Pirenzepine Dihydrochloride,Pyrenzepine,Ulcoprotect,Ulgescum,Dihydrochloride, Pirenzepine,LS 519,LS519,Piren Basan,Pirenzepin Ratiopharm,Von Ct, Pirenzepin
D011976 Receptors, Muscarinic One of the two major classes of cholinergic receptors. Muscarinic receptors were originally defined by their preference for MUSCARINE over NICOTINE. There are several subtypes (usually M1, M2, M3....) that are characterized by their cellular actions, pharmacology, and molecular biology. Muscarinic Acetylcholine Receptors,Muscarinic Receptors,Muscarinic Acetylcholine Receptor,Muscarinic Receptor,Acetylcholine Receptor, Muscarinic,Acetylcholine Receptors, Muscarinic,Receptor, Muscarinic,Receptor, Muscarinic Acetylcholine,Receptors, Muscarinic Acetylcholine
D001743 Urinary Bladder A musculomembranous sac along the URINARY TRACT. URINE flows from the KIDNEYS into the bladder via the ureters (URETER), and is held there until URINATION. Bladder,Bladder Detrusor Muscle,Detrusor Urinae,Bladder Detrusor Muscles,Bladder, Urinary,Detrusor Muscle, Bladder,Detrusor Muscles, Bladder
D004305 Dose-Response Relationship, Drug The relationship between the dose of an administered drug and the response of the organism to the drug. Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D005260 Female Females
D005748 Gastric Fundus The superior portion of the body of the stomach above the level of the cardiac notch. Fundus, Gastric

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