Pharmacological sensitivity of the articular capsule of the primary spines of Eucidaris tribuloides.
1. This paper describes the effects of several cholinergic agonists and antagonists, and of beta-phenylethylamine (PEA) and some of its derivatives, on the articular capsule, or ligament, of the primary spines of Eucidaris tribuloides. 2. Carbamylcholine (CCh), methacholine (MeACh), nicotine, and muscarine exert a stiffening effect similar to that of acetylcholine (ACh), although the time course of their actions varies widely. 3. Atropine induced stiffening and blocked and responses to muscarine and MeACh. The responses to MeACh were blocked also by 4-diphenylacetoxy-N-methylpiperidine, suggesting the presence in the ligament of type M3 muscarinic receptors, in addition to nicotinic ones. d-Tubocurarine induced stiffness of the ligament and failed to block the responses to ACh and nicotine. 4. While ACh induced only a slight desensitization, CCh caused a long-lasting blockade of the stiffening effects of the cholinergic agonists. This shows that the receptors for ACh have a site or sites that recognize the ester moieties of these molecules. 5. Eserine and neostigmine potentiate the responses to acetylcholine, indicating the presence of acetylcholinesterase in the ligament. 6. beta-Phenylethylamine, epinephrine, norepinephrine, and dopamine induce diphasic responses; usually a brief softening followed by a slow and irreversible stiffening of the ligament. 7. In contrast to the above, tyramine and octopamine elicit a simple softening of ligaments which are stiff as a result of handling or by exposure to cholinergic agonists. However, tyramine and octopamine do not soften ligaments which become stiff as a result of exposure to adrenergic agonists.
Morales
M
M
Institute of Neurobiology, University of Puerto Rico, San Juan 00901.
Sierra
C
C
Vidal
A
A
del Castillo
J
J
Smith
D S
DS
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D004347:Drug Interactions; D066298:In Vitro Techniques; D008023:Ligaments, Articular / Q000187:drug effects* / Q000502:physiology; D016210:Methacholine Chloride / Q000494:pharmacology; D009116:Muscarine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D018727:Muscarinic Antagonists; D009538:Nicotine / Q000494:pharmacology; D018733:Nicotinic Antagonists; D009655:Octopamine / Q000494:pharmacology; D010277:Parasympathomimetics / Q000494:pharmacology*; D010627:Phenethylamines / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000502:physiology; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000502:physiology; D012617:Sea Urchins / Q000187:drug effects* / Q000502:physiology*; D012680:Sensitivity and Specificity; D014403:Tubocurarine / Q000494:pharmacology; D014439:Tyramine / Q000494:pharmacology
D002800:Cholinesterase Inhibitors; D018727:Muscarinic Antagonists; D018733:Nicotinic Antagonists; D010277:Parasympathomimetics; D010627:Phenethylamines; D011976:Receptors, Muscarinic; D011978:Receptors, Nicotinic; D016210:Methacholine Chloride; D009655:Octopamine; D009538:Nicotine; D001285:Atropine; D009116:Muscarine; D002217:Carbachol; D000109:Acetylcholine; D014403:Tubocurarine; D014439:Tyramine