Effects of Substance-P on Mechanical Activity of Frog Muscle Fibre

2009 ◽  
Vol 59 (3) ◽  
pp. 254-256 ◽  
Author(s):  
A. Rauf Khan ◽  
Bengt Bengtsson
Keyword(s):  
Substance P ◽  
Muscle Fibre ◽  
Frog Muscle ◽  
Mechanical Activity

The spindle and extrafusal innervation of a frog muscle

1957 ◽  
Vol 146 (924) ◽  
pp. 416-430 ◽  
Keyword(s):  
Muscle Fibre ◽  
Short Distance ◽  
Frog Muscle ◽  
Muscle Fibres ◽  
Intrafusal Muscle ◽  
Intrafusal Fibre ◽  
Unmyelinated Axons ◽  
Intrafusal Fibres ◽  
Break Up ◽  
Tonic System

In the frog muscle, ext. long. dig. IV, there are two or three spindle systems. Each consists of a bundle of intrafusal muscle fibres with two, three or four discrete encapsulated sensory regions distributed in mechanical series along it. A sensory region is usually comprised of the coiled branches of one afferent axon. These embrace the intrafusal fibres and ultimately form long fine varicose endings on or near them. The intrafusal striations appear to be lost for a short distance within the sensory region, and in this region the intrafusal fibre nuclei crowd together. The ‘small’ extrafusal efferents break up into trusses of fine unmyelinated axons and terminate as ‘grape’ end-plates, several of which can occur on the same muscle fibre. This is the ‘tonic’ system. The ‘large’ extrafusal efferents terminate as ‘Endbiischel’ end-plates on muscle fibres not supplied by grape endings. This is the ‘twitch’ system. Both ‘grape' and ‘twitch’ end-plates occur on the intrafusal bundle (probably on separate fibres) between the sensory regions. They are supplied by branches of ‘small’ or ‘large’ axons respectively, which also innervate extrafusal fibres. Thus like the extrafusals the intrafusal bundle is composed of ‘tonic’ and ‘twitch’ muscle fibres. This situation contrasts with that of the mammal, where extrafusals are exclusively ‘twitch’ fibres and intrafusals ‘tonic’.

The Florey Lecture, 1982 Discovery: accident or design?

1982 ◽  
Vol 216 (1204) ◽  
pp. 253-265 ◽  
Keyword(s):  
Electron Microscope ◽  
Muscle Fibre ◽  
19Th Century ◽  
Surface Membrane ◽  
Frog Muscle ◽  
Muscle Fibres ◽  
Personal Factors ◽  
Local Activation ◽  
Microscope Technique ◽  
The 19Th Century

The lecturer reviews the extent to which his own experiments on muscle have followed the course intended when they were planned. His observations on changes in the striation pattern were designed to reinvestigate the formation of ‘contraction bands’, repeatedly observed in the 19th century but neglected more recently. This phenomenon was indeed seen during active shortening,. but the most important outcome consisted of two quite unexpected observations which suggested the existence of a sliding-filament system. Experiments on local activation were planned on the hypothesis that activation was conducted inward from the surface membrane along the Z line. This was apparently confirmed in the first experiments, on fibres from frog muscle, but experiments on muscle fibres from other animals, together with improvements in electron microscope technique, showed that this was a coincidence and that the Z line as such is not involved. Investigation of the transient changes of tension when a stimulated muscle fibre is suddenly shortened required a series of exploratory measurements before a useful hypothesis could be formulated. Some personal factors that have motivated scientists, including Lord Florey himself, are discussed.

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