Über den Einfluss von Desoxycorticosteron auf Kontraktur und Kaliumfreisetzung durch Acetylcholin an der innervierten und denervierten Skelettmuskulatur

Summary The release of potassium ions from striated muscle, and the changes in mechanical tension developed by the gastrocnemius muscle on intraarterial injection of ACh, were investigated by isolated perfusion of the hind limbs in cats. The reaction of the normal innervated and chronically denervated muscle in the same animal were compared before and during perfusion with 2·10^–4 M/l desoxycorticosterone glucoside (DCG). The following results were obtained: after perfusion with DCG no change in the spontaneous release of potassium ions occurred neither on the innervated nor on the denervated muscle. The potassium release following intra-arterial injections of various doses of ACh was significantly reduced on innervated and denervated muscle. On the denervated muscle there was also a considerable reduction of the height of contractures caused by ACh administration. The results make it probable that DCG acts by an inhibition of depolarisation in the same way asd-tubocurarine.     

In-vitro-Versuche über die Methämoglobinbildung durch Chinonderivate

Summary Heubner states that the oxidation of hæmoglobin to methæmoglobin by quinones should be due to a tension between two oxidation-reduction systems, the quinone-hydroquinone system and the hæmoglobin-methæmoglobin system. The authors tried to prove this statement by using various quinones with different oxidation-reduction potentials. An analysis of the results obtained suggests, however, that the oxidation-reduction potential is not the only factor determining the equilibrium. It seems that some other constitutionally conditioned factors also play an important role in this process.Experiments with non-hæmolyzed erythrocytes show that all quinones tested are able to pass through the cellular membrane of the erythrocytes without undergoing any chemical reaction. Thus, the experiments with hæmolyzed solutions and those with intact erythrocytes gave identical results.     

Die Wirkung der Sulfationen auf das Membranpotential der isoliert durchströmten Säugetiermuskulatur

Summary Electrical potential measurements of membrane resting and action potentials were made by means of electrolyte-filled glass micro-electrodes on single fibres of the musculus gracilis of the cat using a perfused hind-limb preparationin situ. The release of potassium from muscle and the tension developed by the gastrocnemius muscle were simultaneously recorded. The normal resting potential in our series was 91.7 mV (s.d. ± 6.7 mV). Partial replacement of the chloride by sulfate in the perfusion fluid led to (a) potassium release from the perfused hind-limb, (b) reversible contracture of the gastrocnemius muscle, (c) depression of the membrane resting potential which was proportional to the degree of replacement of chloride by sulfate in the perfusion fluid and (d) to the occurrence of volleys of spontaneous fibrillation potentials some of which had the shape of damped oscillations. These findings are similar to those observed after treatment with veratrine and are interpreted to be due to (1) increase in sodium permeability and (2) disturbance of the Donnan equilibrium for chloride ions.     

Freisetzung von Kalium aus denerviertem und innerviertem Skelettmuskel durch Acetylcholin

Summary Both hind limbs of cats (one being normally innervated, the other 8–12 days after denervation) were perfused and the quantities of potassium liberated from the two limbs in response to intraarterial injections of varying amounts of acetylcholine were compared by collecting the venous outflow from both sides separately; considerably larger quantities of potassium were found to be liberated from the denervated than from the innervated muscle after equal doses of ACH; the threshold dose of ACH for eliciting a measurable liberation of potassium being much lower on the denervated side. The dose response relation between injected ACH and potassium-liberation is of a different nature for innervated and denervated muscle. The results obtained are compatible with expectations derived from the short circuit theory of the transmitter action on the neuromuscular endplate (Fatt andKatz). The reasons of the difference in the dose relations for the innervated and denervated muscle are discussed.