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Titolo:
RECRUITMENT PATTERNS AND CONTRACTILE PROPERTIES OF FAST MUSCLE-FIBERSISOLATED FROM ROSTRAL AND CAUDAL MYOTOMES OF THE SHORT-HORNED SCULPIN
Autore:
JOHNSTON IA; FRANKLIN CE; JOHNSON TP;
Indirizzi:
UNIV ST ANDREWS,SCH BIOL & MED SCI,DIV ENVIRONM & EVOLUT BIOL,GATTY MARINE LAB ST ANDREWS KY16 8LB FIFE SCOTLAND DUNSTAFFNAGE MARINE LAB OBAN PA34 4AD ARGYLL SCOTLAND
Titolo Testata:
Journal of Experimental Biology
, volume: 185, anno: 1993,
pagine: 251 - 265
SICI:
0022-0949(1993)185:<251:RPACPO>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
PERFORMING OSCILLATORY WORK; POWER OUTPUT; FISH MUSCLE; POLLACHIUS-VIRENS; LENGTH CHANGES; TEMPERATURE; CARP; LOCOMOTION; FIBERS; RED;
Keywords:
SWIMMING; FISH; MUSCLE; CONTRACTILE PROPERTIES; ELECTROMYOGRAPHY; EMG; DUTY CYCLE; SHORT-HORNED SCULPIN; MYOXOCEPHALUS-SCORPIUS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
28
Recensione:
Indirizzi per estratti:
Citazione:
I.A. Johnston et al., "RECRUITMENT PATTERNS AND CONTRACTILE PROPERTIES OF FAST MUSCLE-FIBERSISOLATED FROM ROSTRAL AND CAUDAL MYOTOMES OF THE SHORT-HORNED SCULPIN", Journal of Experimental Biology, 185, 1993, pp. 251-265

Abstract

Muscle action during swimming and the contractile properties of isolated muscle fibres were studied in the short-homed sculpin Myoxocephalus scorpius at 5-degrees-C. Semi-steady swimming, startle responses andprey-capture events were filmed with a high-speed video at 200 framess-1, using fish 22-26 cm in total length (L). Electromyographical (EMG) recordings, synchronised with the video, were made from fast musclein rostral and caudal myotomes at points 0.40L and 0.80L along the body. Fast muscle fibres were first recruited at tail-beat frequencies of 3.7-4.2 Hz, corresponding to a swimming speed of 1.7 L s-1. Electrical activity in the muscles occurred during 16-38 % of each tail-beat cycle regardless of frequency. Muscle fibres were activated during the lengthening phase of the cycle. In caudal myotomes, the onset of the muscle activity occurred at a phase of 75-105-degrees at 3.7 Hz, decreasing to approximately 50-degrees at frequencies greater than 4.5 Hz (0-degrees phase was defined as the point at which muscle fibres passed through their resting lengths in the stretch phase of the cycle; a full cycle is 360-degrees). Prey capture was a stereotyped behaviour consisting of a preparatory movement, a powerstroke at 7-9 Hz and a glide of variable duration. The delay between the activation of muscle fibres in rostral and caudal myotomes during prey capture and startle responses was approximately 10 ms. Fast muscle fibres isolated from rostraland caudal myotomes were found to have similar isometric contractile properties. Maximum tetanic stress was 220 kN m-2, and half-times for force development and relaxation were approximately 50 ms and 135 ms respectively. Power output was measured by the 'work loop' technique inmuscle fibres subjected to sinusoidal length changes at the range of frequencies found during swimming. Under optimal conditions of strain and stimulation, muscle fibres from rostral and caudal myotomes produced similar levels of work (3.5 J kg-1) and generated their maximum power output of 25-30 W kg-1 at the tail-beat frequencies used in swimming (4-8 Hz). Progressively delaying the onset of stimulation relative to the start of the strain cycle resulted in an initial modest increase, followed by a decline, in the work per cycle. Maximum positive work and net negative work were done at stimulus phase values of 20-50-degrees and 120-140-degrees respectively. The EMG and swimming studies suggest that fast muscle fibres in both rostral and caudal myotomes do net positive work under most conditions.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 25/11/20 alle ore 15:16:40