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Characterization of the Cold-Induced Contracture of the Anterior Byssal Retractor Muscle of Mytilus Edulis
1 Department of Physiology and Pharmacology, University ofSt Andrews, Westbum Lane, St Andrews, Scotland; Department of Zoology, University of Maryland, Munich Campus, Postfach 900 760, 8000 Munich 90, W. Germany
When the anterior byssal retractor muscle (ABRM) of Mytilus edulis was subjected to a sudden reduction in temperature during a contractionrelaxation cycle, a tension increment, the cold-induced contracture (CIC), was observed. The CIC could be obtained in a muscle stimulated by the application of acetylcholine (ACh), caffeine or high-K+ solutions, but could not be elicited from a muscle at rest or in catch. When the muscle was released from catch by the application of 5-hydroxytryptamine (5-HT), a CIC could once again be produced. The CIC tension elicited after the application of ACh was shown to follow a log-dose relationship with respect to ACh concentration but no CIC was observed at an ACh concentration at which the initial tension was 10% or less of maximum. The CIC tension decreased with time after the application of ACh and appeared to be dependent on both the initial and final temperatures and on the size of the temperature drop. The significance of these results and possible explanations are considered.
Key words: Anterior byssal retractor muscle, cold-induced contracture, Mytilus edulis
Accepted on April 15, 1985