Thermoelastic tension changes in the muscles of the abdominal stretch receptors of the crayfish

Abstract

1. 1. Under isometric conditions the receptor muscles of the abdominal stretch receptor of Astacus leptodactylus show an anomalous thermoelastic behaviour. 2. 2. Thermoelastic changes in tension increase in proportion with rising preliminary stress and greater parallel-elastic forces. 3. 3. The temporary rise in frequency of the receptor discharge at the beginning of the cooling period is not reflected in the constant fall in muscle tension. 4. 4. The same rate of discharge can be obtained by means of considerably smaller tension changes in the case of thermoelastic than in the case of mechanical strain. 5. 5. As a result of items 2 and 3 the causes for frequency changes after temperature jumps must be sought in temperature-dependent membrane processes in addition to thermoelastic tension changes of the muscle receptor organ (MRO).