Volume 41, Issue 4
April 1955, pages 155-187
pp 155-166 April 1955
pp 167-172 April 1955
pp 173-182 April 1955
1. The properties of the contractile mechanism of unstriated muscle have been studied by recording the contraction of heat killed muscle, produced by raising its temperature to 70° C.
2. The effects of heat show that the contractile mechanism of unstriated muscle consists of two components; in one the relaxation is active and in the other passive. The latter again consists of two parts one of which is activated by heat.
3. The thermal contraction of heat killed unstriated muscle resembles the phasic response of living muscle.
4. The thermal response of heat killed unstriated muscle shows staircase and fatigue effects. It increases with initial length up to a certain point, so that there is an optimum length of muscle for its production. These phenomena in living muscle are therefore properties of the contractile mechanism.
5. Starling’s law of the heart is also shown by thermal contraction of dead muscle.
pp 183-187 April 1955
1. Small concentrations of methyl, ethyl, propyl and butyl alcohols cause active relaxation of the contractile mechanism of unstriated muscle; larger concentrations produce contraction.
2. Copper sulphate, mercuric chloride, carbolic acid and formalin have similar effects.
3. The above substances are known to produce denaturation of proteins in small concentrations and coagulation in higher concentrations; it therefore appears that active relaxation is akin to denaturation and contraction to coagulation of proteins.