ansesthesia; an oncometer was used for measurement of the splenic Laboratory, Cambridge.)

Transcription

1 6I2.4I3:6I2.I43 CAUSE OF RHYTHMICAL. CONTRACTION OF THE SPLEEN. BY J. BARCROFT AN Y. NISIMARU' (Okayama). (From the Physiological Laboratory, Cambridge.) Roy [1881] was the first to discover the rhythmical contractions of the spleen, but they were studied in greater detail by Schaifer and Moore [1896]. This paper is the result of investigation as to the cause of these contractions. The following causes will be discussed in order: (1) change of blood-pressure; (2) temporary stoppage of respiration, and (3) of the circulation in the spleen; (4) injection of salt solution, (5) of haemoglobin solution, (6) of curare solution, (7) of histamine solution; (8) stimulation of the central end of the vagus, and (9) of the central end of the sciatic nerves. METHOD. All our experiments were done on cats under urethane and ether ansesthesia; an oncometer was used for measurement of the splenic volume. (1) CHANGE OF BLOOD-PRESSURE. An increase of splenic rhythm has been described as being due to a rise in arterial pressure by Scihafer and Moore, and also by de Boer and Carroll [1924-5]. The experimental basis of Schiafer and Moore's statement is not clear; in the case of de Boer and Carroll's experiment the rise of blood-pressure was due to the injection of Ringer's solution. It is uncertain, therefore, whether the alteration in the composition of the blood or in the hydrostatic condition initiated the production of the splenic rhythm. Sudden rise of blood-pressure. The following experiments seem to show that a sudden increase of blood-pressure tends, by its direct action on the spleen, to increase the amplitude of the splenic rhythm. This was shown in a cat in which the spleen was denervated, the suprarenals removed, and the central end of 1 Fellow of the Rockefeller Foundation.

2 300 J. BARCROFT AND Y. NISIMARU. the sciatic nerve stimulated for 30 sec. by a Faradic current. As a result of the stimulation the blood-pressure immediately rose, with the alterations in the amplitude of the splenic rhythm seen in Fig. 1. Fig. 1. S. V. splenic volume. B.P. general blood-pressure. T. time, 5 sec. B. base line at 5 mm. Hg. x-x, stimulation of central end of left sciatic nerve. 1/3 original size. In another experiment, in which the spleen was denervated and the suprarenals removed, 25 c.c. of blood were gradually withdrawn from the circulation and then quickly re-injected. The withdrawal produced 1b Fig. 2 a and b. S. V. splenic volume. B.P. general blood-pressure (carotid art.). B. base line at 45 mm. Hg. T. time, 5 sec. x-x, drawing blood. x'-x', injecting blood. 1/3 original size. only a very trifling effect on the curve of splenic volume; but the injection, causing a sudden rise in pressure, produced a well-marked splenic rhythm (Fig. 2a).

3 CAUSE OF SPLENIC RHYTHM. At a later period of the experiment (Fig. 2 b) this procedure was repeated, but with the difference that the injection was slow and the rise in arterial pressure gradual; in this case the splenic rhythm did not occur. Quite similar observations have been made in animals in which the spleen was not denervated. Sudden fall of blood-pressure. When 25 c.c. of blood were removed suddenly, with a corresponding quick fall in blood-pressure, there was always a marked fall in the volume of the spleen, but rhythmical contractions did not appear. (2) TEMPORARY STOPPAGE OF RESPIRATION. 301 Roy, using artificial respiration, found no alteration in the volume of the spleen when the respiration was stopped for about 1 min.; but on the Fig. 3. S. V. splenic volume. B.P. general blood-pressure (carotid art.). T. time, 5 sec. and base line at 20 mm. Hg. x-x, temporary stoppage of artificial respiration. 1/3 original size. resumption of respiration there was a marked contraction of the spleen. Sc h lifer andl Moore, on occlusion of the trachea for a longer time, showed that at a later stage the splenic volume decreased. The ordinary effect, however, of such occlusion was a rise in blood-pressure. In another tracing Sc h ifer and Mo ore gave the result of occlusion of the trachea for only 9 sec. There was, in this case, a sudden rise of blood-pressure andl the beginning of a well-marked splenic rhythm. The cause of this rise of bloodl-pressure is uncertain, but in the light of what has been saidl above the rise of pressure sufficiently explains the appearance of the rhythm. Our experience has been that if the blood-pressure rises slowly during the occlusion of the trachea there is very little effect on the spleen, but if it rises more rapidly the spleen contracts at a later stage; where the bloodpressure falls the spleen remains contracted; but on subsequently giving

4 302 J. BARCROFT AND Y. NISIMARU. air to the animal and causing the blood-pressure to rise rapidly, a wellmarked splenic rhythm is set up. We have also found the same result in the case of the curarized cat, in which the spleen was denervated, the suprarenals removed, and both vagi cut in the neck (see Fig. 3). (3) TEMPORARY STOPPAGE OF THE SPLENIC CIRCULATION. Schafer and Moore found that restoration of the circulation after temporary stoppage produced rhythmic contractions of the spleen even after the nerves had been cut. Their method was to clamp the splenic artery. Our experiment has confirmed this; the only observation which we have to add is that the phenomenon will take place when, in addition, the suprarenals have been removed, as shown in Fig. 4. On removal of Fig. 4. S. V. splenic volume. B.P. general blood-pressure (carotid art.). T. time, 5 sec. B. base line at 30 mm. Hg. x-x, temporary stoppage of splenic circulation. 1/4 original size. the clamp the rise of blood-pressure in the splenic vessels is considerable. We, therefore, can hardly say with certainty that the asphyxial blood causes rhythmical contraction of the spleen. (4) INJECTION OF SALT SOLUTION. There is some difference of opinion as to the effect of intravenous injection of saline. Roy states that he obtained a splenic rhythm by the injection of salt solution. De Boer and Carroll also obtained a marked splenic result; but, as we have already seen, their results can be attributed to rise in blood-pressure. On the other hand, SchAfer and Moore threw doubt on the possibility of a small injection of salt solution producing a splenic rhythm. In our experiments the very slow injection of 4 c.c. of Ringer's solution into the femoral vein, which does not produce any appreciable blood-pressure changes, produces a splenic rhythm; the rhythm is very slight but it is always present. In Exp. 1 we give the actual amplitude of the curves in terms of cubic centimetres of volume change. We obtained similar results on injection of magnesium sulphate (1 c.c. of 6 p.c. solution).

5 303 EXp. 1. Cat No. 97. B. W. 3-8 kg. After the injection of 4 c.c. of Ringer's solution (NaCl-095 g., KCI-0*01 g., CaCl4-001 g., NaCHO,-0 02 g., distilled water 100 oc.), the change of splenic volume was as follows: Before injection During, 1 min. after injection 2,. 3 CA USE OF SPLENIC RHYTHM., Blood-pressure in mm. Hg Undulatory curves appear 138 Rhythmical change of splenic volume 0n The period of rhythm of splenic volume change was 25 sec. (5) INJECTION OF HAEMOGLOBIN SOLUTION. In a number of preliminary experiments there were indications that the injection of haemoglobin solution was of some interest in producing rhythmic contractions of the spleen. In the final experiments the solutions used were prepared by Ad air's method [1925], the solution having finally a ph of 6-8. The result was a slight rise of blood-pressure (confirmingthe recent findings of Mason and Mann [1931]), which gradually faded away, and a gradual increase in the splenic rhythm, which attained a maximum after a considerable time. The time varied in different experiments; in general, the more the htemoglobin injected, the longer did it take to attain the maximal results (Fig. 5). Exp. 2. Cat No. 92. B. W. 5 kg. General blood-pressure (carotid art.), mm. Hg. After the injection of 0.5 c.c. of crude hinmoglobin solution (60 p.c. by Haldane's hbmoglobinometer), which was followed by 1.0 c.c. of Ringer's solution, blood-pressure gradually rose to 140 mm. Hg, and the change of splenic volume gradually increased as follows: Rhythmical change of splenic volume Blood-pressure Crude hsmoglobin in mm. Hg in c.c. Before injection 115 Practically no change During,, miin. after injection 130 0*15 2,, 131 0*18 3,, ,, , ,, 138 0O31 7,, ,, ,, ,, ,, ,, w The period of change of splenic volume was 35 see.

6 304 J. BARCROFT AND Y. NISIMARU. Fig. 5. S. V. splenic volume. B.P. general blood-pressure (carotid art.). B. base line at 45 mm. Hg. T. time, 5 sec. x-x, injection of hemoglobin solution. a, 6 min. after haemoglobin injection. b, 14 min. after hoemoglobin injection. c, 22 min. after injection. d, 39 min. afterheamoglobin injection. e, 103 min. afterinjection. 1/3 original size. Cat No B. W. 3-1 kg. The spleen was denervated and the vessels of both suprarenals ligated. General blood-pressure, mm. Hg. After the injection of 1-5 c.c. of dialysed hemoglobin solution (60 p.c. by Haldane's hamoglobinometer), followed by 1 c.c. of Ringer's solution, the blood-pressure gradually rose and the rhythmical change of splenic volume gradually increased as follows: Rhythmical change Blood-pressure of splenic volume Dialysed hemoglobin in mm. Hg in c.c. Before injection min. after injection ,, 107 0*13 4 go d} ,, ,, ,, ,, ,, , ,, ,, The period of rhythm of splenic volume change was 43 sec.

7 CAUSE OF SPLENIC RHYTHM. 305 This gradual increase in the amplitude of the splenic rhythm was obtained only in response to the injection of haemoglobin solutions. Injection of adrenaline, for instance, produced a rhythm in which the maximal amplitude was immediate, and from that point the curves at once commenced to become shallower. We have given Fig. 5 as an experiment in which purified hsemoglobin was used, the spleen denervated, and the suprarenals tied off; quite similar results, however, were obtained with an injection of crude haemoglobin simply made by the heemolysis of washed corpuscles of the cat's own blood (Exp. 2). The characteristic effect was obtained whether the haemoglobin was from the actual cat used for the experiment or from another. Fig. 6. S. V. splenic volume. B.P. general blood-pressure (carotid art.). B. base line at 40 mm. Hg. T. time, 5 sec. x-x, injection of 3 c.c. of cat's own serum. 1/3 original size. The smallest quantity of haemoglobin injection which gave a recognizable increase of rhythm was 0-l c.c. of a solution 60 p.c. on the Haldane scale (i.e g. per kg. of cat). The following contrql experiments were carried out: (1) injection of the animal's own serum (Fig. 6), (2) injection of buffer, (3) injection of salt solution, and (4) gradual slight increase of blood-pressure. These tests all gave negative results; the rhythm of the spleen increased slightly; it soon disappeared. (6) INJECTION OF CURARE SOLUTION. Roy observed the stimulating effect of curare upon the splenic rhythm, and it was further investigated by Schiifer and Moore, who obtained varying initial results, but there was always a marked increase of splenic rhythm.

8 306 J. BARCROFT AND Y. NISIMARU. Our experience has always been an initial fall in blood-pressure and a rise in splenic volume followed by a splenic rhythm. Our results have been the same whether the spleen was denervated or not, and whether the suprarenals were tied off or not. The difference between our findings and those of Schiafer and Moore may have been due to the fact that we had a much higher bloodpressure; or it may have been due to some peculiarity of the sample of curare used. (7) INJECTION OF HISTAMINE SOLUTION. Though the pharmacological action of histamine on various organs has been studied by many investigators, so far as we know its action on the splenic rhythm has not yet been studied. In the case of intact Fig. 7. S.V. splenio volume. B.P. general blood-pressure (carotid art.). T. time, 5 sec. B. base line at 50Tmm. Hg. x-x, injection of histamine ( mg. per kg.). 1/3.2 original size. cats, the injection of mg. of histamine phosphate per kg. into the femoral vein produces a sudden fall of the general blood-pressure, as is well known, and at the same time a decrease in splenic volume. After these initial changes, the blood-pressure rises to the previous level, but the spleen shows rhythmical changes of volume as seen in Fig. 7. Since there is always the change of blood-pressure in the case of intact animals, we can hardly say whether the action of histamine on the spleen is direct or is indirect, depending on the blood-pressure change. But this will be explained in the following experiment on the excised and perfused spleen. An excised spleen was perfused with the cat's own defibrinated blood, through which 6 p.c. CO2 was bubbled with air. During the experiment the fluid was kept at a constant temperature of 38 C., and also at a constant pressure of 80 mm. Hg. An oncometer, in which the spleen and cotton-wool, wet with Ringer's solution, were contained, was kept warm at 38 C. Under these circumstances the injection

9 CA USE OF SPLENIC RHYTHM. 307 of mg. of histamine produced a remarkable contraction of the spleen (Fig. 8), but after the initial contraction splenic rhythm was not clear, as in the case of the intact animal. (8) STIMULATION OF THE CENTRAL END OF THE VAGUS NERVE. Roy and Schiafer and Moore stated that the stimulation of the central end of the vagus produces a fall in the spleen volume in the dog. Bayliss1, stimulating the depressor in the rabbit, obtained an increase in spleen volume, and the same was obtained by Masuda [1926-7] who stimulated the central end of the vagus in the cat and found that a rhythm was also set up. He obtained these results with both vagi and with the left sympathetic, but not with the right sympathetic which is Fig. 8. B P. pressure of perfused blood (80 mm. Hg). S. V. splenic volume. T. time, 5 sec. x, injection of histamine. 1/3 original size. said to be free from depressor fibres. We have confirmed the findings of Masuda on the cat and, in addition, found that when the spleen is denervated, the spleen decreases in volume when these nerves are stimulated. (9) STIMULATION OF THE CENTRAL END OF THE SCIATIC NERVE. Roy found that when the central end of the sciatic nerve was stimulated, as the general arterial pressure rose the spleen shrank and a rhythm ensued. This we confirmed, and in addition we found that if the spleen was denervated it dilated as the blood-pressure rose, and a rhythm ensued. In the case of the innervated spleen the contraction was due to direct nervous influence on the spleen; in the case of the denervated spleen the dilatation was due presumably to the sudden rise in bloodpressure. 1 (Thisinformationis not to befoundin Bayliss' published works, but maybe gathered from thelegendof Fig. 445of the fiftheditionof Starling's Principles of Human Physiology, London, It is not discussed with referenge to the function of the spleen.)

10 308 J. BARCROFT AND Y. NISIMARU. (10) EXCISED AND PERFUSED SPLEEN. The rhythmical change of splenic volume in the case of intact animals has already been mentioned; but does this rhythm occur in the case of the excised and perfused spleen? S chaifer and Mo ore stated that rhythmic contraction and dilatation of the excised spleen of the dog, perfused with warm defibrinated blood of the same animal,.were only small but quite obvious, and the activity of the movements was increased by temporary stoppage of the flow of blood through the organ; however, their curves do not clearly show the rhythmical change of splenic volume. In our experiments, the rhythmical contraction and dilatation of the excised and perfused spleen of the cat have been shown as clearly as those of the spleen of the intact animals. The excised spleen was perfused with Fig. 9. S. V. splenic volume. B.P. pressure of perfused blood. T. time, 5 sec. x-x, change of blood-pressure. 1/3 original size. the cat's own defibrinated blood through which 6 p.c. 002 was bubbled with air. The perfusion fluid and the oncometer containing the spleen and cotton-wool, wet with Ringer's solution, were kept at a temperature of 380 C. A perfusion pressure of 80 mm. Hg was used. Under these circumstances a sudden temporary increase of pressure resulted in rhythmi'cal changes of splenic volume (Fig. 9). Blood-pressure was changed from 90 mm. Hg to 158 mm. Hg for 10 sec. The splenic volume passively increased by 1*7 c.c. and then followed rhythmical changes of splenic volume of 1-9c.c., 0-85 c.c., 0-62 c.c., 0-5 c.c., 0-5 c.c., 0-S c.c. Period of waves was 35 sec. SUMMARY. 1. A sudden rise of general blood-pressure produces an initial passive dilatation of the spleen which is followed by rhythmical contractions of the spleen, but a sudden fall of general blood-pressure produces only a

11 CAUSE OF SPLENIC RHYTHM. 309 passive contraction of the spleen. Similar results are also obtained when the spleen is denervated and the suprarenals are removed, and when the excised spleen is perfused with defibrinated blood. 2. During the stoppage of respiration the spleen volume is affected slightly, but upon giving air to the animal and so causing the bloodpressure to rise rapidly, a well-marked splenic rhythm is set up. The same result occurs when the spleen is denervated and the suprarenals are removed. 3. Restoration of the splenic circulation after its temporary stoppage is quite effective in producing the rhythmical contraction of the spleen, and it makes no difference whether or not the spleen is denervated or the suprarenals removed. 4. The injection of salt solution produces a slight increase of rhythmical change in the spleen. 5. The injection of haemoglobin solution causes remarkable rhythmical volume changes in the spleen. The feature which distinguishes injection of haemoglobin from all other methods which we have used for the production of splenic rhythm is the characteristic gradual increase in amplitude of the splenic waves. 6. The injection of curare causes an initial fall in blood-pressure and a rise in splenic volume, followed by splenic rhythm. Our results are the same whether the suprarenals are tied off and the spleen denervated or not. 7. The injection of histamine causes an initial fall in blood-pressure and a fall in splenic volume, followed by splenic rhythm. In the case of an excised and perfused spleen histamine causes contraction, but this is followed by little or no rhythm. 8. We have confirmed Masuda's experiments on the stimulation of the central end of the vagus, and in addition we have observed that, if the spleen be denervated, stimulation of the central end of the vagus causes a decrease of the splenic volume instead of an increase. The decrease is of course the result of the fall in general arterial pressure. 9. We have confirmed Roy's experiment that on the stimulation of the central end of the sciatic nerve the spleen shrinks, and we have observed that after denervation of the spleen similar stimulation causes an increase of the splenic volume instead of a decrease. 10. The rhythmical contraction occurs in the excised and perfused spleen as strongly as in the spleen of the intact animal.

12 310 J. BARCROFT AND Y. NISIMARU. REFERENCES. Adair, G. S. (1925). Proc. Roy. Soc. A, 108, 627. de Boer, S. and Carroll, D. C. (1924-5). J. Phy8iol. 59, 317. Mason, J. B. and Mann, F. C. (1931). Amer. J. Phy8iol. 98, 181 Masuda, T. (1926-7). J. Phy8iol. 62, 289. Roy, C. S. (1881). J. Physiol. 3, 203. Schifer, A. E. and Moore, B. (1896). J. Physiol. 20, 1.