The effect of varying tonicity on the anaphylactic and other reactions of plain muscle / by H.H. Dale.

  • Henry Hallett Dale
Date:
[191 ?]
Catalogue details

Licence: Public Domain Mark

Credit: The effect of varying tonicity on the anaphylactic and other reactions of plain muscle / by H.H. Dale. Source: Wellcome Collection.

    21/26 page 535
    But, dealing only with the results described in detail in previous sections, they may be summarised as follows: 1. Any increase in the tonicity of the Ringer’s solution, in which isolated plain muscle is suspended, has an inhibitor effect on tonus; any decrease in tonicity acts as a stimulus. 2. When the change in either direction is too small to cause a rise or fall of tonus by itself, or when the plain muscle has adjusted itself to the new conditions, the subsequent effect of a stimulant drug is decreased, that of an inhibitor drug increased, by a«rise in tonicity, while a fall in tonicity produces the oppo¬ site effects in both cases. 3. The protective effect of strong saline injections in the ana¬ phylactic shock of the guinea-pig is readily explicable, as a par¬ ticular case of the depressant effect of raised tonicity on the response of plain muscle to stimulant drugs. It does not seem desirable at the present stage to attempt to base on these results any positive conclusions as to the mechanism of plain muscle contraction. At first sight, indeed, the apparent dependence of the effect on the tonicity of the solution only, and its independence within limits of the nature of the salt or non-electrolyte to which this is due, seems to be inconsistent with theories which attribute contraction to imbibition of water (Quellung) by the muscle-colloids. It must be botne in mind, however, that we are dealing with living cells, freely permeable to water, but relatively impermeable to sodium ions or cane- sugar. The immediate effect of changes in the osmotic pressure of the bathing-fluid, whatever the substance to which the osmotic pressure is due, will be to withdraw water from, or add water to the constituents of the muscle fibers, thereby raising or lower¬ ing the concentration of their intrinsic salts. Since the inter¬ change in contraction is regarded as taking place between fibrils and interfibrillar substance, and not between the whole organ and the fluid bathing its surface, there is no necessary inconsis¬ tency between the facts here presented and an imbibition theory of contraction. With one particular view of the nature of plain- muscle contraction, on the other hand, they seem to be definitely discordant. This is the theory of Meigs, according to which the
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