Efectos respiratorios del Micorén

Abstract

133

In experiences of dogs Micorén action is studied. Above all the response of the glottis, which is not described by other authors, is studied. The effects of the slow intravenous injection in non-anaesthetized dogs is observed and in dogs in a state of respiratory depression due to anaesthetics or a strong dose of antitussive drugs. The effectiveness of the analeptic actíon whích increases the respiratory minute volume in all animals is checked. lt is observed that the characteristics of the respiratory movements change somewhat throughout the time in which the minute volume remains increased. The most characteristic graphs ín a normal animal and in one whose respiratory centre was prevíously depressed are shown ín fig. 2. It is notíced that once the phase of rapid frequency has passed, rapid inspirations of great depth appear. The movements of this type appear intercalated in the register periodical!y and even in sorne moments in short sequence interrupted by movements of this kind. The most evident of these results is that the stimulating action of the Micorén affects the inspiration very markedly. On the other hand the expiratory activity only sligtly increases in the initial phase of the response as can be appreciated by the slight rise in the pleural pressure as compared with the rest breathing of the animal. Besides in nonanaesthetized animals spontaneons breathing is usually fast, accompanied by irregular contractions of the expiratory muscles; these contractions decrease or disappears altogether from the moment of the injection which regularizes the breathing rhythm.
Glottis resistance. -In the non-anaesthetized animal the glottis resistance to the flow of air increases during expiration and decreases during inspiration. In our experimental conditions this variation is registered by an increase in pressure of few centimetres of water in rest breathing and disappears in anaesthesia.
In all our experiments on non-anaesthetized animals, the Micorén produced a marked increase in resistance in expiration (fig. 2), already clearly visible before the intravenous injection is finished; it reaches a maximun in a few moments. In general while this effect lasts the glottis relaxes normally on inspiration, but in sorne experiments, during a series of movements the increase in resistance remains -even on inspiration (fig. 3), with a spasmodic, character comparable wíth the response to the deep inhalation of ammonia (fig. 3,2).
Influence on the effect, comparing accesses of controlable cough with accesses under the effect of Micorén, we brought on coughing by insufflating powdered soap and, will the object of gething the most uniform cünditions in ali the experiments, we insufflated the same amount of soap in the same part of the trachea. Even when this type of stimulation has not been sufficient quantitative, it is enough for an approximate valuation. The Micorén seems to help the cough response brought on by tracheal excitations in most cases, though the result, if we judge by the intensity of the contractions of the expiratory muscles, is clearly visible in sorne experiments only (fig. 4).
Fig. 1.- Breathing minute volume in three typical experiments. A and B, a normal non-anaesthetized dog; C and D, dogs in a state of depression in breathing due to a strong dose of codein and to anaesthesia respectively.
Fig. 2.- From top to bottom, intraperitoneal pressure (PAb ), pleural pressure (PPl) and neumotacograma (NTG).
A, non anaesthetized dog. 1, control; 2, immediately on termination of injection of Micorén (5 mg./Kg.); 3, nine minutes after; B, non-anaesthetized dog. 1, effect of codein injection to toxic dose, immediately before the Micorén injection; 2, termination of Micorén injection (5 mg./Kg.); 3, eight minutes after.
Fig. 3.- From top to bottom, glottis resistance, pleural pressure and arterial pressure. The arrow marks the termination of the Micorén injection.
Fig. 4.- 1, glottis spasm two minutes after the Micorén injection (10 mg./Kg.); 2, cough due to inhalation of ammonia; 3, cough due to intravenous injection of lobeline; 4, cough due to insufflation of soap in the trachea.
Fig. 5.- From top to bottom, intraperitoneal pressure (PAb ), pleural pressure (PPl), and neumotacograma. 1, immediate registration of insufflation of control soap; 2, immediate registration on insufflation of soap 4 minutes after the Micorén injection.