On The Electrotonic Spread in Cardiac Muscle of the Mouse

I N T R O D U C T I O N I t is a well k n o w n fac t t h a t t h e ca rd iac muscle fibers m a k e compl ica ted anas tomoses w i th each o ther . T h i s makes analysis of t h e tissue electr ical proper t ies very diff icult c o m p a r e d w i t h ne rve a n d skeletal musc le fibers. A t t empt s , however , h a v e been m a d e to app ly l inear cab le analysis t o ca rd i ac muscle, for example , to t h e false t e n d o n wh ich has less b r a n c h e d , i.e. relat ively l inear cablelike fea tures ( W e i d m a n n , 1952), a n d to t h e t e rmina l P u r k i n j e f iber as a n equ iva len t l inea r cab le consisting of several c o m p o n e n t fibers a t t a c h e d side b y side ( M a t s u d a , 1960). W o r k i n g on t h e r a t a t r i u m , W o o d b u r y a n d Crill (1961) proposed a p l a n a r m o d e l for the ca rd i ac tissue. T h e y showed theoret ical ly a n d exper imenta l ly t h a t the spat ia l d i s t r ibu t ion of a tonical ly app l i ed po ten t ia l a t a n y po in t of a cell in ter ior in the tissue c a n be m a t h e m a t i c a l l y expressed b y a Bessel func t ion .