Influence of potassium on contractility of bronchial muscle

Abstract

On studying the influence of the ionic equilibrium on experimental histaminic asthma of the guineapig, it has been observed that the intravenous injection of potassic chloride determines a diminution of the volume of air expired —fairly proportional to the dosis— which in themajority of experiments. We further observe that the intracarotid injec­ tion in an ascendent sense to the ordinary, determines an increase ofexpired air, probably by stimulus of the bulbar centers and úischarge of the sympathetic nerve. The reduction of the volumen of expired air is not observed if aleudrin or aminophilin is injected inmediately beforehand.

Doses higher than 2 mg. of potassic chloride intravenously given, exercise an inhibiting influencie upon the bronchioconstrictor effect of histamin which is injected afterwards, in direct relation to the dosis of chloride, and this inhibition persists during five minutes. On the other hand, if injected at the same time as histamin, they seem to strengthem same

Doses of potassic chloride less than 2 mg. never produce any appreciable effect. Doses of 2 mg. always strengthen the effect of histamin a fact which may be connected with the clinical observation of discrete hyperpotassemies in bronchial asthmatic patieuts.

The injection of potassic chloride intraperitoneally immediately inhibits the efect of histamin, but is recuperated after a few minutes, sometimes with a certain tendeney to increase.

The response to acetylcholine is influenced by strong doses of potassic chloride, approximately equal to the response to histamin.

Potassic chloride at strong doses given intravenously strengthens 5 in 20 % of the experiments the bronchiodilator effect of adrenalin. We have not observed in our experiments that intraperitoneal injection of potassic chloride modifices the action of adrenalin, seeing that modification of bronchial resistance appears at the injection and besides inhibition continues as before the histamin injected aftewards.

On the contrary the inhibiting action of aminophilin to histamin disappeared, as if the potassic chloride injected in the peritonium of the guineapig would inhibit the effect of amnophilin on histamin.