Volume 20, Issue 5
November 1944, pages 143-204
pp 143-174 November 1944
pp 175-186 November 1944
pp 187-191 November 1944
pp 192-194 November 1944
The excitation produced by vagus stimulation has an inhibitory component.
Tonus is antagonistic to vagus stimulation.
The optimum temperature for vagus stimulation is 30° C.
The optimum concentration of calcium is about 0·05-0·07 M CaCl, potassium about 0·06 M KCl and hydrogen ions, pH 7·8-7·4.
The stimulation produced by vagus and acetylcholine does not belong to the potassium group. It resembles more that produced by alternating current.
pp 195-204 November 1944
Excitatory phenomena in unstriated muscle can be explained if it is assumed that the muscle consists of two zones, outer and inner, and excitation be due to difference in concentration of ions in these two zones. Moderate increase in permeability would diminish the excitability to alternating current and increase that to potassium; great increase would dimmish the excitability to both. An increase in the permeability of the outer membrane by physiological action, injury, asphyxia would cause excitation or inhibition. Spontaneous contractions are caused by increase in permeability, not great enough to cause continuous tension. Substances to which the muscle is moderately permeable, such as sodium and barium, produce continuous tension as they are unable to enter the inner zone. Substances to which the muscle is more permeable such as ammonium or potassium produce only a temporary contraction.