Abstract
The present paper deals with an analysis of the action of parathormone on the neuromuscular system which may be considered the main seat of the tetany syndrome (MacCallum and Vogel 1 ) The hind legs of pithed Ranae esculentae were perfused with phosphate buffered Ringer and the sciatic nerve stimulated with rhythmic condensor discharges as described previously. 2 After a state of relative fatigue had been reached in which the height of contraction remains equal over a long period of time, the perfusion fluid was exchanged for one containing parathormone, Lilly or Parke Davis, in concentrations from 1:1000 to 1:100. In all solutions the pH was carefully adjusted to that of Ringer. The phenol content proved to be without effect as control experiments indicated. In several hundred experiments parathormone invariably causes an increase in the height of contractions up to about 200% in the strongest concentrations. The effects are reversible when the solution is again exchanged for ordinary Ringer and the effects are due to the parathormone content of the extract for the following reasons:
1. Extracts of the parathyroid which according to the blood calcium test show the same number of units per cc. but contain solids of varying concentrations show an equal effect on the muscle even when the concentration of the solids varies 100%.
2. Boiling for one hour destroys neither the action of parathormone on the blood calcium (Collip and Thomson 3 ) nor our reaction.
3. Destruction of the hormone content of the extract by boiling with 10% HC1 for one hour abolished the described reaction on the muscle, as it does the blood calcium effect according to Collip.
Get full access to this article
View all access options for this article.