Plasticity of Muscle Contractile Properties Following Temperature Acclimation in the Marine Fish Myoxocephalus Scorpius

Toni A. Beddow, Ian A. Johnston
1995 Journal of Experimental Biology  
Live fibre bundles were isolated from the fast myotomal muscle of short-horned sculpin (Myoxocephalus scorpius L.) and isometric contractile properties and the force-velocity (P-V) relationship determined at 5, 10 and 15 °C. Experiments were carried out on winter-and summer-caught sculpins and on individuals acclimated for 6–8 weeks to either 5 or 15 °C (12h:12h light:dark). Maximum tetanic tension (P0) in fibres from 15 °C-acclimated fish increased from 125 kN m−2 at 5 °C to 282 KN−2 at 15 °C
more » ... R10=2.3). For 5 °C-acclimated fish, Po was 139 kN m−2 at 5 °C, but fell to 78 kN m−2 at 15 °C, consistent with a partial failure of excitation-contraction coupling at high temperatures. Peak force at 15 °C was increased 2.2 times following depolarisation with a high-K+ solution, but was unaffected by the addition of caffeine and/or eserine to the Ringer's solution. The results from winter-and summer-caught fish were similar to those from 5 °C-and 15 °C-acclimated sculpins respectively. In 15 °C-acclimated fish, the power output of muscle fibres calculated from the P-V relationship was 55W kg−1 at 5 °C and 206 W kg21 at 15 °C. The P-V relationship at 5 °C was significantly less curved in muscle fibres from 5 °C-than from 15 °C-acclimated fish. After normalizing the curves for P0 and Vmax, it was found that the change in curvature was sufficient to produce a 40 % increase in relative power output at 5 °C in cold-acclimated fish. The maximum contraction speed of muscle fibres at 15 °C was 2.4 times higher in 15 °C-than in 5 °C-acclimated fish. It was concluded that acclimation modifies the contractile properties of fast muscle fibres at both low and high temperatures.
doi:10.1242/jeb.198.1.193 fatcat:7wmaczvrmnaj7gxqkfxdulm2va