Cholinergic control of the mechanical properties of the catch connective tissue in the holothurian body wall

Effects of acetylcholine (ACh), ACh-agonists and antagonists were studied on the viscosity of the dermis of the sea cucumber Holothuria leucospilota. ACh and nicotinic agonists caused an early increase in viscosity and late decrease. Muscarinic agonists produced a viscosity decrease. The viscosity increase elicited by nicotine was inhibited by tubocurarine. The viscosity decrease caused by methacholine was suppressed by atropine. The mechanical properties of this connective tissue are very likely controlled by both nicotinic and muscarinic cholinoreceptors.