The first evidence that electrical changes can cause muscles to contract
was p- vided by Galvani (1791). Galvani's ideas about 'animal
electricity' were explored during the 19th and 20th century when it was
firmly established that 'electricity' is one of the most important
mechanisms used for communication by the nervous system and muscle.
These researches lead to the development of ever more soph- ticated
equipment that could either record the electrical changes in nerves and
muscles, or elicit functional changes by electrically stimulating these
structures. It was indeed the combination of these two methods that
elucidated many of the basic principles about the function of the
nervous system. Following these exciting findings, it was discovered
that electrical stimulation and the functions elicited by it also lead
to long-term changes in the properties of nerves and particularly
muscles. Recent findings help us to understand the mec- nisms by which
activity induced by electrical stimulation can influence mature, fully
differentiated cells, in particular muscles, blood vessels and nerves.
Electrically elicited activity determines the properties of muscle
fibres by activating a sequence of signalling pathways that change the
gene expression of the muscle. Thus, elect- cal activity graduated from
a simple mechanism that is used to elicit muscle c- traction, to a
system that could induce permanent changes in muscles and modify most of
its characteristic properties.
