Mechanisms of hypersensitivity to histamine after B. pertussis vaccination in rats were studied, and it was demonstrated that the lethal effect of histamine might be causally related to an induction of hypercalcemia. The increase in serum calcium seemed to be mainly due to a liberation of calcium from the kidney and the liver. It was inferred that the hypercalcemia was responsible for the induction of serious cardiac irregularities which was the main cause of acute death after histamine injection in the vaccinated rats.

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1. Calcium dependency of the stimulating effect of excess potassium on lipolysis and oxygen consumption was examined in the rat interscapular brown adipose tissue in vitro.
2. The metabolic effects of excess potassium were markedly decreased in calcium free medium. This effect of calcium omission was more pronounced in lower doses of excess potassium and was partially overcome by increasing the concentration of potassium. Similar pattern of inhibition was also obtained in the presence of excess magnesium. In white epididymal adipose tissue, excess potassium showed no significant stimulation on free fatty acid release.
3. On the other hand, lipolytic effect of norepinephrine on brown adipose tissue was only partially reduced by calcium omission or excess magnesium.
4. Lipolytic activity of brown adipose tissue and the ionic effect on it were discussed in relation with the role of cyclic 3', 5'-AMP and calcium ions.

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The ATPase activities and Ca-binding of skeletal microsomes were measured under various conditions and the effects of degradation of the microsomal membrane on the ATPase activities and Ca-binding were investigated.
1. Microsomal ATPase was activated by either Ca or Mg, and the activity increased with increases in the concentration of Ca or Mg. However, when both Ca and Mg were added to the reaction mixture, the ATPase showed a maximum value of the activity in respect to the concentration of either Ca or Mg. The values Km and Vmax of the Ca- or Mg-activated ATPase increased with increases in the concentration of Ca or Mg. The values of K_m and V_max of Ca-activated ATPase were maximum at pH 8.0; those of Mgactivated ATPase at pH 7.5.
2. A small amount of Ca was bound to the microsomes even in the absence of ATP. Ca-binding of the microsomes increased markedly on addition of ATP, and furthermore, the Ca-binding in the presence of ATP increased with increases in the concentration of Mg. Reciprocals of the amounts of bound Ca, 1/(bound-Ca), were in linear relation to 1/(free-Ca), 1/(ATP) and 1/(Mg). Ca-binding of the microsomes in the absence of ATP slightly increased at alkaline pH, whereas Ca-binding in the presence of ATP showed a maximum value at pH 6.0 and decreased at alkaline pH.
3. Mg-activated ATPase was resistant to proteolytic digestion, whereas Mg and Ca-activated ATPase and Ca-binding were markedly inhibited by it. During digestion, peptides of low molecular weight were released from the microsomes. Mg and Ca-activated ATPase activity was enhanced by a brief incubation with phospholipase A, and then inhibited on longer exposure. Mg-activated ATPase activity was to some extent decreased by the treatment with phospholigase A and no enhancement of the activity was observed. Ca-binding was quickly inhibited by the treatment. Sonication of the microsomes caused decreases in the ATPase activities and in Ca-binding.
4. Mg-activated ATPase activity was gradually inhibited by addition of urea, DOC or ethanol, whereas Mg and Ca-activated ATPase activity was enhanced by urea or DOC and attained to a maximum value at 1.5 M of urea and at 10-s M of DOC, beyond which both compounds inhibited the enzymic activity. Ca-binding was markedly inhibited by addition of urea, DOC and ethanol.

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The transmembrane impedance of the squid giant axon was measured for a wide frequency range from 50 Hz to 1 MHz.
The impedance locus was not an exact circular arc, but it showed a clear deviation from it at the high frequency range. Such an impedance locus can be expected, if the axon membrane impedance has at least two time constants. An equivalent circuit model having two time constants was introduced. Each element of the circuit remained constant for the change in frequency.
The capacity of the axon membrane decreased by 10-25 per cent, when the membrane was depolarized by adding 80-100 mM potassium ion externally. Decrease of external sodium ion concentration down to half or increase of external calcium ion concentration from 10 mM to 60 mM had no appreciable influence on the capacity.

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From experimental results in the excised toad heart, the following characteristics of cardiac afferents can be summarized:
1. There are two types of afferent fibers in the cardiac nerve; myelinated and nonmyelinated afferent fibers. The diameter range of myelinated afferent fibers was 3 microns to 8 microns.
2. The area of the receptive fields of mechanoreceptors belonging to these two types of nerve fibers were usually spot-like and distributed in the atrial and ventricular wall of the heart. They were also found in the venous sinus. In general, they tended to be slowly adapting.
3. Mechanoreceptors in the ventricular wall are mainly localized in the endocardial or subendocardial muscular layer.
4. On the basis of conduction velocities, it is suggested that the mechanoreceptors activated synchronous with the heart beat belong to the myelinated afferent fibers.

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Parotid fluid was collected without exogenous stimulation from 513 healthy young male adults, and under rubber band and sour lemon drop stimulation from 271 subjects from the same population. The mean unstimulated parotid flow rate was 0.027 ml/min, the Na concentration mean was 2.61 mEq/1, and that for K was 36.7 mEq/1.
In six subgroups of the unstimulated subjects, flow rate did not exert a significant effect on Na concentration, but there was a highly significant negative correlation between K concentration and rate of flow; the mean for [K+] ranged from 25.5 mEq/1 at the highest rate of flow, to 46.3 mEq/1 at the lowest rate.
In the stimulated saliva samplings, the most dramatic effect was the marked increase in [Na+] and rate of secretion, the mean [Na+] at the highest rate of secretion (lemon drop stimulated) being 66.26 mEq/1. Potassium con-centration fell from the unstimulated level, and then remained constant at two different levels of stimulated flow (ca. 18 mEq/1).
The low Na and high K levels found in unstimulated saliva are felt to result from reabsorption of Na in excess of water and the secretion of K into the luminal fluid by ductal cells. The lack of effect of flow rate on Na con-centration within the flow rate range of the present study may result from a balanced outward diffusion of water from the luminal fluid caused by Na reabsorption.

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The circulating blood volume of healthy adult male volunteers was meas-ured at 12: 00, 18: 00, 24: 00 and 06: 00 under controlled conditions (200 ml fluid intake every three hours, constant supine position, constant room temperature and illumination).
Under these conditions, the circulating blood volume was significantly lower (about 6%, P<0.001) at 24: 00 than at 12: 00 or 18: 00. On the other hand, the hematocrit, measured at the same time, was constant throughout the day. Plasma protein and serum Na and K were slightly, but significantly less at 24: 00 than at 18: 00. An increase of about 5% in the erythrocyte volume in blood depots during the night was observed from the simultaneous determination of the erythrocyte volume and plasma volume. Causal factors of circadian variation of circulating blood volume in this controlled experiment were discussed but the complete explanation of the results remains for further experiments.
The circadian variation in the circulating blood was also measured on subjects during normal active daily life. In these, the circulating blood volume was almost identical at 12: 00 and 24: 00, while the hematocrit decreased by 3.6%(P<0.001).
From these result, it is concluded that erythrocyte is deposited in depots during the night, with concomitant dilution of the blood, so that the circu-lating blood volume remains almost constant with sub jects of normal routine activities.

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1. Both the sinus-and AV node arteries of the canine heart in vivo were simultaneously perfused at a constant pressure of 100 mmHg.
2. The selective administration of 0.1 to 0.3μg of norepinephrine into the AV node artery caused a shortening of the PQ interval, and the P wave eventually disappeared after a dose of 1 to 10μg. An inverted P wave was occasionally observed just before the disappearance of P wave. Thus the AV nodal tachycardia was induced when the pacemaker shifted from the sino-atrial node to the AV node. When the AV nodal rhythm reverted to the sinus rhythm in the course of recovery, the sinus rate decreased at first below control before being stabilized at the original value.
3. Atrial fibrillation resulting from the administration of acetylcholine into the sinus node artery did not occur when the pacemaker activity had been made to shift to the AV node.
4. The induction of atrial fibrillation to be induced by injection of acetylcholine into the sinus node artery was blocked even when the dominance of pacemaker activity in the right atrium was induced by electric pacing.
5. When the dominant pacemaker in the atrioventricular node was established successfully by injection of norepinephrine into the AV node artery, sustaining atrial fibrillation was blocked.
6. It was concluded that the dominant activity of sino-atrial pacemaker is necessary for induction and maintenance of atrial fibrillation by acetylcholine.

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Properties of nociceptors excited by acetylcholine in the hindlimb were investigated on conscious dogs utilizing vocalization as a measure of nociception. All compounds were administered into the femoral artery through a chronically indwelling catheter. Acetylcholine and two nicotinic compounds, nicotine and DMPP, produced vocalization, withdrawal or shaking of the hindlimb, biting and struggling. Three muscarinic compounds, bethanechol, methacholine and McN-A-343, failed to cause any sign indicative of nociception in the hindlimb even with large doses producing severe signs of generalized parasympathetic excitation. The nociceptive responses to acetylcholine were blocked by prior (1 to 2 min) administration of hexamethonium, tetraethylammonium, or DMPP in doses equal to those of acetylcholine, but not by comparable doses of l-hyoscyamine. The nociceptive responses to equi-effective doses of histamine or bradykinin were not affected either by any of these blockers. These results indicate that the afferent neuroreceptors which give rise to the nociceptive responses to acetylcholine administered into the femoral artery are nicotinic in nature.

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The changes in the medullary and cortical blood flows of isolated dog kidney were measured by means of a light and small thermocouple inserted in each region.
When the perfusion pressure rose abruptly, the medulla responded increasing the flow independently of the initial perfusion pressure, while the cortical flow varied according to the initial perfusion pressure value. From 70 to 160 mm Hg of initial perfusion pressure, the cortex showed a doublehumped response, that is, an initial increase in blood flow f ollowed by a decrease that did not reach the control value and finally a late increase. The urinary flow increased concomitantly with the late increase in the cortical blood flow. When the initial perfusion pressure was under 70 mm Hg or over 160 mm Hg the cortex responded similarly to the medulla.
The α adrenergic blocking agent (MA 1277) did not change any of the responses above mentioned but potassium cyanide (4 mM/L in the perf using blood) suppressed the decrease in blood flow shown by the cortex, in such a way that only an increase was observed. Under KCN action the urinary flow increased simultaneously with the increase in the perfusion pressure. The intra-arterial in jection of acetylcholine, in doses of 2.5 μg/g of kidney tissue, produced a decrease in the cortical blood flow while the medullary blood flow responded by an initial increase followed by a decrease. These responses were concomitant with a decrease in the total renal flow. When the MA 1277 was added (5 mM/L) to the perfusing blood the response to acetylcholine mentioned above, changed in such a manner that only increases in the cortical, medullary and total renal blood flows were observed. The different effects of large doses of acetylcholine on cortical and medullary resistance are discussed in terms of different amount of sympathetic transmitter released.
The present findings suggest that during an abrupt increase in the perfusion pressure the diminution phase of the double-humped cortical flow response was caused by an active contraction of the vascular smooth muscles; while the increment in medullary flow could be due to the blood coming from another source different from the efferent blood vessels of the juxtamedullary glomeruli.

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