QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gunzel, D. Articles by Rathmayer, W. Search for Related Content PubMed Articles by Gunzel, D. Articles by Rathmayer, W.

Journal of Experimental Biology, Vol 175, Issue 1 267-282, Copyright © 1993 by Company of Biologists

JOURNAL ARTICLES

FIBRE HETEROGENEITY IN THE CLOSER AND OPENER MUSCLES OF CRAYFISH WALKING LEGS

D. Gunzel, S. Galler and W. Rathmayer

1. The closer and opener muscles in the third walking legs of the three crayfish Pacifastacus leniusculus, Procambarus clarkii and Astacus leptodactylus are composed of fibres which differ in histochemistry, electrophysiology and morphology. Three major groups of fibres (A, B and C) were distinguished. 2. Group A fibres react weakly to histochemical stains for myofibrillar ATPase (mATPase) activity characteristic of fibres with slow shortening speeds. In the opener muscle, they are innervated by the opener excitor (OE) and the specific opener inhibitor (OI). In the closer muscle, group A fibres are innervated by the common inhibitory neurone (CI) in addition to single (slow closer excitor, SCE) or double excitatory (SCE and fast closer excitor, FCE) innervation. Group A fibres have the largest excitatory junction potentials (EJPs), the longest membrane time constants (tau) and the longest sarcomeres. They are located at the very distal and proximal ends of both muscles. 3. Group B fibres show higher mATPase activity than group A fibres. In the opener muscle, they are innervated by OE and OI; in the closer muscle, they receive double excitatory (SCE and FCE) and CI innervation. Single SCE and OE EJPs are small; those caused by FCE are larger. tau is shorter than in the other two fibre groups. Sarcomere lengths lie between those of group A and C fibres. Group B fibres are found along the entire lengths of both muscles. 4. Group C fibres exhibit the highest mATPase activity (characteristic of fibres with fast shortening velocity) which, in contrast to the ATPase of group B fibres, is not resistant to alkaline preincubation at pH 10.05. In the closer, these fibres lack innervation by CI, otherwise the innervation pattern is identical to that of group B fibres. EJP size is similar to that of group B fibres; tau ranges between values for group A and B fibres. Sarcomere lengths are the shortest of all the fibre types. Group C fibres constitute the majority of the fibres in the two muscles and mainly occupy the central regions.

This article has been cited by other articles:

				W. M. Kier and F. H. Schachat Muscle specialization in the squid motor system J. Exp. Biol., January 15, 2008; 211(2): 164 - 169. [Abstract] [Full Text] [PDF]

				W. M. Kier and N. A. Curtin Fast muscle in squid (Loligo pealei): contractile properties of a specialized muscle fibre type J. Exp. Biol., July 1, 2002; 205(13): 1907 - 1916. [Abstract] [Full Text] [PDF]

				D. L. Mykles, S. Medler, A. Koenders, and R. Cooper Myofibrillar protein isoform expression is correlated with synaptic efficacy in slow fibres of the claw and leg opener muscles of crayfish and lobster J. Exp. Biol., February 15, 2002; 205(4): 513 - 522. [Abstract] [Full Text] [PDF]

				M. E. Crider and R. L. Cooper Differential facilitation of high- and low-output nerve terminals from a single motoneuron J Appl Physiol, March 1, 2000; 88(3): 987 - 996. [Abstract] [Full Text] [PDF]