title: Power output and force-velocity relationship of red and white muscle fibres from the Pacific blue marlin (Makaira nigricans).
abstract: Single white fibres and small bundles (two to three) of red fibres were isolated from the trunk muscle of Pacific Blue Marlin (50-121 kg body weight). Fibres were chemically skinned with 1% Brij. Maximum Ca2+-activated force production (Po) was 57 kN m-2 for red fibres and 176 kN m-2 for white fibres at 25 degrees C. The force-velocity (P-V) characteristics of these fibres were determined at 15 and 25 degrees C. Points below 0.6 Po on the P-V curve could be fitted to a linear form of Hill's equation. The degree of curvature of the P-V curve was similar at 15 and 25 degrees C (Hill's constant a/Po = 0.24 and 0.12 for red and white fibres respectively). Extrapolated maximum contraction velocities (Vmax) were 2.5 muscle lengths s-1 (Lo S-1) (red fibres) and 5.3 Lo S-1 (white fibres) at 25 degrees C. Q10(15-25 degrees C) values for Vmax were 1.4 and 1.3 for red and white fibres respectively. Maximum power output had a similar low temperature dependence and amounted to 13 W kg-1 for red and 57 W kg-1 for white muscle at 25 degrees C. The results are briefly discussed in relation to the locomotion and ecology of marlin.
mesh_terms: D000818:Animals; D005399:Fishes / Q000502:physiology*; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology; D013696:Temperature