The Sarcomere Length-Tension Relation in Skeletal Muscle

I N T R O D U C T I O N T e n s i o n d e v e l o p m e n t d u r i n g an i s o m e t r i c t e t a n u s in ske le ta l musc le occu r s in t h r e e d i s t inc t phases : t en s ion ini t ia l ly r ises r a p i d l y , t h e n c l imbs m o r e s lowly, a n d f ina l ly r e a c h e s a p l a t e a u which lasts m a n y s e c o n d s . T h i s t i m e c o u r s e is o b s e r v e d d u r i n g i s o m e t r i c c o n t r a c t i o n s o f musc les ( A b b o t t a n d A u b e r t , 1952; De leze , 1961), musc l e f i b e r b u n d l e s (Sugi , 1972) a n d s ingle f ibe r s ( R a m s e y a n d S t r e e t , 1940; E d m a n , 1966; G o r d o n et a l . , 1966 b), as well as in musc l e f i b e r s e g m e n t s h e l d at c o n s t a n t l e n g t h d u r i n g the t e t a n u s ( G o r d o n et a l . , 1966 b). O n the basis o f ce r t a in e x p e r i m e n t a l o b s e r v a t i o n s (see Discuss ion) G o r d o n et al . (1966 b) f o u n d c o n v i n c i n g r a t i o n a l e fo r a s s u m i n g t ha t t he slow c l imb o f t e tan ic t e n s i o n o r in t h e i r t e r m s , t he " c r e e p " was solely d u e to the d e v e l o p m e n t o f p r o g r e s s i v e d i s p e r s i o n o f s a r c o m e r e l eng ths : " T h e r e can be l i t t le d o u b t J. GEN. PHYSIOL. 9 The Rockefeller University Press 9 0022-1295/78/1001-056551.00 565 Volume 72 October 1978 565-592 on Jne 1, 2017 D ow nladed fom Published October 1, 1978