The effect of temperature on the tension responses of the anterior byssal retractor muscle (abrm) of Mytilus edulis.

The effect of ambient temperature on the response of the ABRM of Mytilus edulis to acetylcholine and 5-hydroxytryptamine has been examined. As the ambient temperature was increased, the latent period and the maximum tension developed decreased while the rate of tension development and the rate of relaxation increased. The relationship between temperature and the rate of tension development showed three distinct linear phases from 2-25, 25-35 and 35-45 degrees C. The reduction in peak tension with temperature could also be resolved into three portions from 2-25, 25-40 and above 40 degrees C. As the temperature was increased above approximately 27 degrees C the rate of relaxation in the absence of 5-HT approached the rate of relaxation in the presence of 5-HT. The significance of these results and possible explanations for them are considered.