Sunita Inderjit Singh
Articles written in Proceedings – Section B
Volume 19 Issue 4 April 1944 pp 130-146
Volume 21 Issue 5 May 1945 pp 259-265
Frogs were encountered, the stomachs and hearts of which were refractory to the action of acetylcholine, even after eserine. In the hearts, the beats were augmented by acetylcholine, but diminished by vagus stimulation. They could be tetanised, and the responses with electrical stimulation were graded. The aurides and ventricles beat rhythmically but independently in the absence of electrolytes.
Volume 23 Issue 6 June 1946 pp 301-311
Volume 25 Issue 1 January 1947 pp 1- Erratum
Volume 25 Issue 3 March 1947 pp 51-56
The responses of avian plain muscle in general resemble those of mammalian plain muscle.
Eserine has little or no potentiating effect on the action of acetylcholine.
In sodium deficient solutions, the gut elongates activity when stimulated with alternating current.
In a muscle inexcitable to nervous stimulation, alternating current produces its usual effects.
Volume 25 Issue 6 June 1947 pp 163-172
The nature of response of frog’s stomach muscle to nervous stimulation is described. The contraction is similar to that produced by acetylcholine and potassium, and is not of the same type as that produced by alternating current, suggesting that acetylcholine is liberated during nervous stimulation of frog’s stomach. Excitation by nervous stimulation appears to involve the potassium ion.
Nervous stimulation also produces a contraction similar to that produced by alternating current, thus suggesting that electrical transmission precedes chemical. It is suggested that chemical transmission imparts tome properties to the effects of electrical transmission.
On nervous stimulation, circular fibres of the stomach give the second kind of contraction, and longitudinal the first kind or tonic contraction. It is probable that the function of the longitudinal fibres is to maintain a tonic pressure on its contents and prevent the sagging of the stomach, and that of the circular fibres is to mix the contents by rhythmic contractions, as well as to exert a tonic pressure.
Volume 26 Issue 5 November 1947 pp 211-217
The properties of the contraction produced by break of a constant current are similar to those of the alternating current off-contracture; the make contraction resembles that produced by alternating current.
The muscle responds to break of a constant current when it may be inexcitable to all other forms of stimulation; it may respond when all the sodium chloride of the saline is replaced with chlorides of lithium, ammonium, potassium, calcium, magnesium and strontium or in acid solutions (pH 5).
Magnesium and adrenaline abolish the break contraction.
The response differs with polarity of the direct current; this suggests that the permeability of the membranes is different in the two directions. Stimulation by alternating current is probably due, therefore, to rectification.
The make and the break contractions bear a reciprocal relation to each other.
With polar stimulation, the results are very complicated; contraction or inhibition may occur at the anode or the cathode on make or break of the current.
Volume 27 Issue 5 May 1948 pp 127-136
Asphyxia at first increases the response of frog’s unstriated muscle; this is followed by diminution and then paralysis. These effects are also produced by cyanide. This increase in excitability is not abolished by iodoacetic acid.
Asphyxiai arrest is relieved by glucose, potassium and the other substances that produce tonic contraction.
In the presence of oxygen the muscle becomes hyperirritable in acid solutions and so possesses different aerobic metabolic mechanisms in alkaline and acid solutions respectively.
In acid solutions, pH 6, sodium lactate, acetate and propionate improve the response to alternating current.
Asphyxia does not produce rapid arrest of movement in muscle poisoned with iodoacetic acid.
In a muscle poisoned with iodoacetic acid, then exhausted by frequent stimulation in asphyixia, and then revived by oxygen, sodium lactate and sodium butyrate improve the response. Glucose, glycine, sodium acetate and propionate have no effect.
In asphyxia, tone at first decreases and then increases; this asphyxiai contraction is identical with tone that does not use oxygen.
Volume 28 Issue 2 August 1948 pp 51-55
The neuromuscular junction in frog’s unstriated muscle is more susceptible than the muscle to fatigue, toxic action of substances and oxygen lack.
Calcium and potassium are necessary for neuromuscular transmission.
Spontaneous contractions and those produced by electric current are myogenic.
Volume 30 Issue 1 July 1949 pp 47-56
There is a glycolytic system in unstriated muscle for acid solutions, as shown by the effect of glucose in improving the response both aerobically and anaerobically.
The glycolytic system for acid solutions is antagonistic to that for alkaline solutions.
Both the ærobic and anaerobic mechanisms for tone and twitch respectively are different both in acid as well as in alkaline solutions.
Potassium postpones or hastens asphyxiai arrest.
Calcium also has similar action.
Tone producing substances act similarly to potassium.
Riboflavine improves the response aerobically as well as anaerobically. Thiamine, ascorbic acid and nicotinic acid have no such action.
Sudden increase of osmotic pressure of the saline relieves asphyxiai arrest.
Glucose has inhibitory effect also in the presence of oxygen.
Fatty acids, such as acetic, propionic and butyric also improve the response in the presence of oxygen.
Inexcitability is of two kinds: one due to changes in the excitatory process, and other due to exhaustion of energy supplies.
Volume 30 Issue 2 August 1949 pp 95-98
Volume 30 Issue 3 September 1949 pp 168-175
Asphyxia at first increases the responses to potassium and acetyl-choline, then depresses them.
The decline of excitability is affected by the nature of tone.
The resistance to asphyxia of various responses varies in the following order: Nervous stimulation < electrical stimulation < acetylcholine < potassium.
Tone-producing substances depress the response of asphyxiated frog’s unstriated muscle, if the latter is stimulated about once in 10–15 minutes. In mammalian muscle the result is opposite.
Glucose has at first an inhibitory and then a stimulatory action on the response of unstriated muscle to potassium; if the metabolism is increased by raising the temperature, then, the effect becomes stimulatory the outset.
Iodoacetic acid increases the response to potassium after a preliminary depressant effect.
pH 6 increases the response to acetylcholine and potassium after a preliminary depressant effect.
Volume 30 Issue 4 October 1949 pp 215-225
One kind of asphyxial increase in excitability is inhibited by glucose and increased by iodoacetic acid and acid solutions.
The second kind of asphyxial increase in excitability is increased by glucose and inhibited by iodoacetic acid and acid solutions.
The mechanism, which produces the glycolytic asphyxial increase in excitability is antagonistic to the non-glycolytic one.
Glucose is utilised anaerobically in two ways; one of these is the same as that in which it is utilised ærobically, and the other is antagonistic.
Tone producing substances depress the response of asphyxiated muscle to alternating current if the latter is stimulated about once in 10–15 minutes.
There are two anaerobic mechanisms in acid solutions; one is antagonistic to and the other same as aerobic one,
During asphyxial increase in excitability, inhibition may be turned into contraction.
Volume 30 Issue 5 November 1949 pp 263-269
At 20° C., dog’s stomach muscle shows the first asphyxiai contraction, but not the second.
At 20° C., glucose loses its inhibitory action, but that of oxygen is increased; at higher temperature, the reverse happens.
At 20° C., iodoacetic acid and cyanide also do not produce contraction.
If the second asphyxiai contraction is prevented mechanically or if developed, is abolished mechanically, then the power to contract on asphyxiation is permanently lost. Twitch contractions can be produced, but not tonic contractions. This suggests a separate contractile mechanism for tonic contraction (alactic tone).
Volume 30 Issue 5 November 1949 pp 270-278
Volume 30 Issue 6 December 1949 pp 343-368
Dog’s stomach muscle and the human appendix relax actively after being stimulated.
Dog’s stomach muscle relaxes actively during inhibition and accommodation.
Relaxation is of two kinds, active and passive.
Active relaxation is diminished by asphyxia, cyanide and partially restored by glucose.
Active relaxation is diminished by iodoacetic acid.
Active relaxation is diminished by substances that produce tonic contraction, such as potassium, ammonium, lithium, sodium, barium, hydrogen, ions, calcium, strontium, magnesium, bromide, nitrate, iodide, thiocyanate, acetylcholine, pilocarpine, nicotine, eserine, adrenaline.
Methyl and ethyl alcohols diminish active elongation in small and increase in large concentrations.
Active elongation is diminished by hypo- and hypertonic solutions.
The optimum pH for active elongation is 8.
The optimum temperature for active elongation is 30° C.
Substances that depress the vitality of the muscle cause contraction by antagonising active elongation.
Volume 31 Issue 6 June 1950 pp 351-356
Frog ’s and dog ’s stomach show the predominance of alactic tone in the pyloric regeion and lactic tone in the cardiac region.
The tone in the pyloric region has the properties of the asphyxial contraction.
The tension due to tonic contraction of the pyloric muscle can be destroyed without affecting the twitch contraction suggesting that these two are mediated by different contractile mechanisms.
Stretching of muscle antagonises elongation produced by distilled water and other substances.
The muscle from the pyloric and cardiac regions behave differently in distilled water. The former contracts and the latter relaxes. These reactions are produced both in living as well as dead muscles, so it is concluded that unstriated muscle contains two kinds of contractile proteins for lactic and alactic tones respectively.
Stretching increases the tendency to contraction and decreases that to inhibition. Asphyxia also produces similar effects.
When increased demand is made on unstriated muscle with normal oxygen supply or normal demand with diminished oxygen supply, it puts into action a contractile mechanism which does not require energy.
Volume 32 Issue 1 July 1950 pp 12-22
Volume 33 Issue 2 February 1951 pp 100-100 Erratum
Volume 33 Issue 4 April 1951 pp 165-177
A comparative study of the contractile mechanism of frog’s, dog’s and
Sodium and potassium chlorides have identical action on the three kinds of muscles. Barium chloride and sodium cyanide cause contraction of the contractile mechanism of unstriated muscle of
Contraction of the contractile mechanism of unstriated muscle are of two kinds. One kind is relaxed by swelling of the muscle and the other kind not. Relation of this finding to the tonus mechanism is discussed.
Action of ammonium, calcium, strontium, magnesium, bromide, nitrate, iodide and thiocyanate is described. Potassium, magnesium relax the contractile mechanism.
The excitatory and the contractile mechanism of unstriated muscle have been dissociated by destroying the former by high voltages (110–880 volts A.C.) and by methyl alcohol. Action of substances on the contractile mechanism has then been studied.
If normal tone of the muscle is destroyed, then the asphyxiai contraction does not occur, proving the identity of the two.
Volume 33 Issue 4 April 1951 pp 184-191
Volume 35 Issue 4 April 1952 pp 167-180
Volume 35 Issue 5 May 1952 pp 214-224
Volume 35 Issue 6 June 1952 pp 245-250
Substances that cause excitation, hasten recovery from electrical inhibition. As inhibition is identical with accommodation, these experiments support the view, that accommodation to excitation is due to the liberation of inhibitory substances, and accommodation to inhibition, due to liberation of excitatory substances.
Volume 37 Issue 5 May 1953 pp 188-196
Experiments have been performed on dying muscles. In such muscles, the excitatory system is destroyed and the substances act directly upon the contractile mechanism. The excitatory system was also rendered inoperative by chloroform.
In such muscles 0·1–0·3
Urea and thiourea produce active relaxation. As urea is also known to produce dissociation of actomyosin, these experiments suggest that the dissociation of actomyosin is of two kinds, one producing active and the other passive relaxation.
Many salts which produce dissociation of actomyosin produce relaxation.
Distilled water causes active relaxation.
The effect of potassium chloride has been tested on living
Volume 40 Issue 5 November 1954 pp 125-137
A new technique is described to determine the action of substances on the contractile mechanism of unstriated muscle. It consists in killing the muscle by heating it to 50° C. for a few minutes.
The results obtained on heat killed muscle are more or less similar to those on dying muscle with minor differences.
Active relaxation occurs if the muscle is heated to 50–60° C. As heat denatures the proteins, it appears that the process of relaxation of muscle is similar to that of denaturation of proteins. Most substances that denature proteins, cause unstriated muscle to relax actively. These experiments therefore throw light both on the process of relaxation and on that of denaturation of proteins.
Urea, sodium cyanide, distilled water, formamide, acetamide, acids and alkalies cause active relaxation of heat killed muscle.
Potassium chloride has similar action on heat killed muscle as on dying muscle. It causes two or three kinds of contraction. One of these is antagonised by calcium, and probably corresponds to superprecipitation of actomyosin. The other contractions are probably due to some other proteins.
The effect of sodium chloride resembles that of potassium chloride.
Possible mechanisms of tonus are discussed.
Volume 40 Issue 5 November 1954 pp 145-160
Volume 41 Issue 2 February 1955 pp 47-64
Volume 41 Issue 4 April 1955 pp 173-182
1. The properties of the contractile mechanism of unstriated muscle have been studied by recording the contraction of heat killed muscle, produced by raising its temperature to 70° C.
2. The effects of heat show that the contractile mechanism of unstriated muscle consists of two components; in one the relaxation is active and in the other passive. The latter again consists of two parts one of which is activated by heat.
3. The thermal contraction of heat killed unstriated muscle resembles the phasic response of living muscle.
4. The thermal response of heat killed unstriated muscle shows staircase and fatigue effects. It increases with initial length up to a certain point, so that there is an optimum length of muscle for its production. These phenomena in living muscle are therefore properties of the contractile mechanism.
5. Starling’s law of the heart is also shown by thermal contraction of dead muscle.
Volume 41 Issue 4 April 1955 pp 183-187
1. Small concentrations of methyl, ethyl, propyl and butyl alcohols cause active relaxation of the contractile mechanism of unstriated muscle; larger concentrations produce contraction.
2. Copper sulphate, mercuric chloride, carbolic acid and formalin have similar effects.
3. The above substances are known to produce denaturation of proteins in small concentrations and coagulation in higher concentrations; it therefore appears that active relaxation is akin to denaturation and contraction to coagulation of proteins.
Volume 42 Issue 3 September 1955 pp 85-89
Volume 42 Issue 4 October 1955 pp 172-182
1. The reaction of blood vessels to sodium and potassium ions have been studied: (
2. The effect of the above ions on the contractile mechanism of the smooth muscle of the arterioles was studied by the dying muscle technique and by prior heating to 50°C.
3. Sodium has a contractile and potassium, a relaxing effect on the contractile mechanism of the smooth muscle of the arterioles. This explains the role of sodium in essential hypertension.
Volume 42 Issue 4 October 1955 pp 183-190
1. The action of cholesterol on the excitatory and the contractile mechanisms of unstriated muscle has been described.
2. Cholesterol causes contraction of dog’s and frog’s stomach muscle by action on the excitatory system. It changes the nature of tone, so that the muscle is unable to relax.
3. Cholesterol increases the tone of the blood vessels of dog’s hind limbs.
4. Cholesterol causes contraction of the contractile mechanism of unstriated muscle; this contraction is dependent upon the ionic balance.
5. It is concluded that cholesterol may be active in later stages of hypertension, in increasing tonus of arterioles, and producing irreversibility.
Volume 42 Issue 4 October 1955 pp 191-194
1. The action of calcium on the contractile mechanism of the unstriated muscle of the arterioles has been studied by prolonged immersion of dog’s hind limbs in solutions of calcium chloride and recording the rate of flow before and after immersion for 24 hours.
2. Isotonic solutions of calcium chloride produce a strong irreversible contraction of the arterioles. This is due to the action of calcium on the contractile mechanism.
3. The possible role of calcium in hypertension has been discussed.
Volume 42 Issue 6 December 1955 pp 300-310
Volume 43 Issue 1 January 1956 pp 62-66
1. The action of lead on the excitatory and contractile mechanism of smooth muscle is described. The latter has been determined by testing the effect of lead on dying and heat killed muscles.
2. Lead causes contraction of smooth muscle and arterioles by direct action on the contractile mechanism. This action may be of significance in producing contraction of smooth muscle in the body and in producing hypertension.
Volume 43 Issue 2 February 1956 pp 89-94
Volume 51 Issue 6 June 1960 pp 249-254
1. In frog’s heart, on electrical stimulation, more acetylcholine per g./wt. is liberated from the lower half of the ventricle which is free from ganglion cells, than from the rest of the heart which contains ganglion cells. This suggests that acetylcholine mainly originates from the muscle cells.
2. The acetylcholine per g./wt. content of the ganglion free portion of the ventricle is greater than the rest of the heart which contains ganglia. This shows that acetylcholine is also contained in muscle cells besides nerve cells.
Volume 52 Issue 2 August 1960 pp 33-42
1. Frog’s heart (
2. Spontaneously beating frog’s heart releases adrenaline and noradrenaline.
3. Stimulation of the sympathetic nerves releases adrenaline as well as noradrenaline.
4. After fatigue of the sympathetic nerves by maximal stimulation for one hour, direct electrical stimulation releases adrenaline and noradrenaline in amounts greater than can be released by nervous stimulation. These hormones therefore can originate from muscle cells.
Volume 52 Issue 4 October 1960 pp 116-118