Inderjit Singh

The effect of the interaction of ions, drugs and electrical stimulation as indicated by contraction of the anterior retractor of the byssus of mytilus edulis

WINTON [1937] has described the results of stimulating this plain muscle with alternating current (A.C.) and direct current (D.C.). The present series of observations is concerned with describing the properties of the contraction produced by these and various other agents, with a view to attempting an analysis of the interrelation between ions, drugs and electrical stimulation in respect of their potentiating or antagonizing actions. The significance of the relations discovered in connexion with contraction has been extended by a preliminary analysis of the effects of the relevant agents on the water and total base content of the muscle [Singh, 1938].

Properties of tonic contractions produced by electrical stimulation of the anterior retractor of the byssus of Mytilus edulis

WINTON [1937] has described the tonic contraction of Mytilus muscle produced by stimulation with direct current (D.C.). Singh [1938b] has described the properties of tonic contractions produced by certain ions. In this paper are described the properties of tonic contractions produced as a result of stimulating the muscle with alternating current (A.C.) or D.C. In previous papers [Singh, 1938b, c, d] it has been suggested that tonic contractions of high viscosity are due to action of ions present outside the muscle fibres, while the A.C. contraction, characterized by low viscosity, is due to action of ions present inside the muscle fibres. In this paper an attempt has been made to show that tonic contractions produced as a result of stimulating the muscle with A.C. or D.C. are also due to the action of ions present outside the muscle fibres.

Certain effects of pulmonary gas embolism.

DUNN [1920], working with Barcroft, showed that a considerable proportion of the pulmonary vessels could be blocked without diminution in the blood flow through the lungs. Torracca [1922] briefly described the morbid anatomical findings after the intravenous injection of considerable quantities of oxygen to guinea-pigs. Binger, Brow and Branch [1924a, b] studied the cause of the respiratory disturbances produced during pulmonary embolism, while Barry [1929] investigated the electrocardiographic and respiratory changes in pulmonary gas embolism. The present experiments are in continuation of work on the intravenous injection of oxygen [Singh, 1935], certain of the effects of pulmonary gas embolism being studied in detail.

A comparative study of the effect of the interaction of ions, drugs and electrical stimulation as indicated by contraction of unstriated muscle

THE experiments performed on Mytilus unstriated muscle [Singh, 1938 a, b, c, d, e, f, 1939] have been extended to the unstriated muscle of frog stomach. The environment of the former is quite different from that of the latter, and it was deemed expedient to repeat on frog muscle some of the experiments performed on Mytilus muscle, in order to see whether some of the conclusions arrived at previously were of general applicability.

The effect of stretching and of stimulation on the weight, total base and sodium concentration of the anterior retractor of the byssus of mytilus edulis

To study the effect of stimulation on the total base of Mytiltus unstriated muscle, it was necessary to stretch the muscle to hold it in place. It was found that stretching alone produced changes in weight and total base concentration of the muscle; so before studying the changes in the total base induced by electrical stimulation, changes produced by stretching alone were investigated. Some observations in connexion with the effect of chemical stimulation on the weight of the muscle were also recorded.

Factors affecting the sodium, potassium and total base content of the anterior retractor of the byssus of mytilus edulis

SMOOTH muscle contains less potassium and more sodium than skeletal muscle. A high sodium potassium ratio has been found by Saiki [1908] in pigs stomach; by Constantino [1911] in ox stomach, ox retractor penis, cow uterus and fowl stomach, the uterus being particularly low in potassium; by Meigs & Ryan [1912] in frog stomach; by Wilkins [1934] in cow uterus and bladder. The following experiments were performed to determine the sodium potassium and the total base content of Mytilus muscle and to study the conditions affecting the passage of sodium and potassium ions into and out of the muscle. EXPERIMENTAL

The effect of the interaction of ions, drugs and electrical stimulation as indicated by the contraction of mammalian unstriated muscle

Human unstriated muscle differs from unstriated muscle of lower animals in the following respects: n n(1) n nThe optimum temperature for excitability is higher, 37°. n n n n n(2) n nMany substances affect the tone as well as the excitability to alternating current and potassium similarly. It is suggested that this is due to decrease of adaptation, as an increase produces inhibition.

Tonus in unstriated muscle

Summary and ConclusionNo single explanation of tonus in unstriated muscle can suffice as there are two kinds of tonic contractions, one with and the other without oxygen usage. The former is akin to ordinary contraction and the latter to some structural change in muscle. It is suggested that in tonic contractions without oxygen usage, myosin forms a stable compound with some ions in the muscle fibres, while in twitch such a compound is unstable. The two factors which combine with myosin to form the contractible compounds of tonic and twitch contractions respectively are mutually exclusive in their combination with myosin; this explains many tonic and twitch phenomena in unstriated muscle.

The mode of action of drugs on unstriated muscle and the nature of inhibition

Summary(1)Both adrenaline and acetylcholine produce contraction of unstriated muscle in the electrolyte-free medium, suggesting that their action is due to mobilisation of ions within the fibres.(2)They also produce contractions or inhibitions resembling those produced by ions outside the fibres; this suggests that they may also act by sensitising the muscle to ions outside.(3)Acetylcholine produces two kinds of contractions in the unstriated muscle.(4)Inhibition is really an excitatory process, masked by adaptation.(5)Adrenaline inhibition is antagonised by potassium, ammonium, electric current, hydrogen ions, and increase in osmotic pressure; it is potentiated by calcium, hydrogen ions, and also by electric current. Adrenaline thus produces two kinds of inhibitions.(6)Eserine acts by means other than combining with choline-esterase.(7)Ephedrine potentiates adrenaline also by a process of summation.(8)Drugs produce a contraction, which is a class by itself.(9)The optimum temperature for adrenaline inhibition is 30°

The mode of action of potassium on unstriated muscle

Summary and Conclusions(1)The action of potassium, calcium and sodium suggest that they exist in the combined and free form in the unstriated muscle, they respectively determine the excitatory, inhibitory and tonic and viscous states in the muscle.(2)One of the actions of potassium is due to its difference in concentration on the two sides of the muscle membrane. This is shown by the fact that the optimum concentration of potassium in the saline for excitability depends upon its concentration inside the fibres. For maximum excitability there is an optimum ratio of potassium on two sides of the muscle membrane.(3)The second action of potassium is probably on the cell membrane as it is antagonised by calcium.(4)A third action of potassium is probably on the muscle colloid as it affects the viscosity of the muscle.