38

Bioelectromagnetism

with the combination of galvanometers and diferential rheotomes and recorded the rest and action

potential time course in the range of several tens of microseconds and conduction velocity of nerve

impulse from isolated nerve fbers of frogs. A diferential rheotome is an instrument that enables electri­

cal connections to be made for extremely short, but nevertheless precise time intervals (McComas, 2011).

He showed that the action potential has a rapid rise and a rather slower decay, the total duration being

less than a millisecond (McComas, 2011). Tis diferential rheotome consists of three parts: a turntable

with a diameter of 20 cm, a Ruhmkorf induction coil for a stimulator, and recording is done with a

galvanometer. Bernstein’s investigation was facilitated by the use of Lippmann’s capillary electrometer.

Tis meter is a more sensitive instrument than the astatic galvanometer. Tis capillary electrometer

was used in the measurement of the action potential of nerves. Gabriel Jonas Lippmann (1845–1921), a

French physicist, invented the capillary electrometer in 1873, which is a tube of ordinary glass, 1 m long

and 7 mm in diameter flled with mercury, and the capillary’s tip point is immersed in dilute sulfuric

acid. Lippmann was the winner of the Nobel Prize in Physics in 1908 for his method of reproducing

colors photographically based on the phenomenon of interference.

In 1902, afer many important contributions to electrophysiology, Bernstein assumed that the mem­

brane is permeable to a single ion and proposed the primitive semipermeable form of the membrane

theory of action potential across the cell membrane. Cell membrane is able to selectively pass a certain

kind of ions. According to this theory, the semipermeable membrane surrounding the cell upon excita­

tion becomes permeable to potassium ions which enter the cell from the surrounding tissue fuids and

give rise to a state of polarization on the surface of the cell (Rowbottom and Susskind, 1984). His experi­

ments were facilitated by the use of Lippmann’s capillary electrometer. However, the formation of the

membrane theory of Bernstein was still incomplete. His hypothesis was that the potential diference

across the cell membrane was maintained by the diference of ion concentrations, permeable to potas­

sium ions, and impermeable to intracellular anions and sodium ions, which is the concept of a semi-

membrane. His membrane theory was the basis for the evaluation that the transmembrane voltage was

as proportional to the logarithm of the concentration ratio of the potassium ions, which was expressed

by the Nernst equation. He was recognized as the founder of the membrane theory.

Te German school made great contributions in physiology, in particular in electrophysiology from

the second half of the nineteenth century. Historically, Bernstein’s membrane theory was a shif in

electrophysiological research into bioelectric phenomena and laid the background for bioelectromagne­

tism. Tis background led to international research which began in the 1930s by Alan Lloyd Hodgkin,

Andrew Fielding Huxley (1917–2012) (England), Howard James Curtis (1906–1972) (USA), Herman Paul

Schwan (1915–2005), and Kenneth Stewart Cole and John Carew Eccles (1903–1997) (Australia). Te

development of electrophysiology gave signifcance to the applications of electricity in medicine, to elec­

trotherapy and magnetotherapy.

As a basis for bioelectromagnetism, two works by Japanese scientists are introduced. Te two discov­

eries contributed greatly to the development of electrophysiology. Gen-ichi Kato (1890–1979) was born

in Okayama Prefecture, Japan, physiologist and professor at Keio University (Kato, 1970). In 1923, he

proposed the decrementless conduction of the nerve impulse in the presence of a narcotic agent. Tree

years later, the XII International Physiological Congress was held in Stockholm. Kato and his assistant

attended this Congress to perform an experimental demonstration of decrementless nerve conduction

with Japanese toad (Bufo vulgaris Japonicus). Tis Japanese toad has long nerves due to its large size.

During this travel from Japan through Siberia to Stockholm, all of the Japanese toads turned out to

be dead. So, they used Dutch toads instead of Japanese toads. Either way, they were successful in the

demonstration. In addition, Kato and his group made the successful isolation of a single nerve fber in

conducible state in 1930. In 1935, Ivan P. Pavlov (1849–1936), a Russian physiologist and 1904’s Nobel

Prize Laureate, nominated Kato as a nominee for the Nobel Prize in Physiology or Medicine for his work

on isolation of single nerve fbers and muscle fbers and for the demonstration of the existence of refex

excitatory fbers and refex inhibitory fbers.