Acetylcholine sensitivity of the spine-test articular capsule of the sea urchin Eucidaris tribuloides.
1. The changes in the consistence of the spine-test articular capsule, or ligament, of the primary spines of Eucidaris tribuloides induced by acetylcholine (ACh) have been studied. Two complementary techniques were used: (a) "forced-vibration", which detects variations in the stiffness of the ligament along a single diametral plane; and (b) "forced-rotation" which records the spatial distribution of those changes. 2. ACh (1 microM to 1 mM) caused a rapid increase in the resistive force opposed by the ligament to passive stretching. Similar effects were elicited by several monoquaternary, N-substituted derivatives of trimethylammonium. 3. The opposite effect, i.e. softening, was induced by decamethonium, dimethylphenylpiperazine, and 2-ketoamyltrimethylammonium. 4. The involvement in these effects of ACh-binding groups with pharmacological properties similar to those of the "anionic sites" of nicotinic ACh receptors is suggested.
Morales
M
M
Institute of Neurobiology, UPR-MSC, Old San Juan, Puerto Rico 00901.
del Castillo
J
J
Smith
D S
DS
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D008023:Ligaments, Articular / Q000187:drug effects; D010277:Parasympathomimetics / Q000494:pharmacology; D011950:Receptors, Cholinergic / Q000032:analysis; D012399:Rotation; D012617:Sea Urchins / Q000187:drug effects*; D014732:Vibration
D010277:Parasympathomimetics; D011950:Receptors, Cholinergic; D000109:Acetylcholine