1) Temperature-sensitive neurones in the preoptic region of rats anesthetized with urethan were examined for responsiveness to iontophoretically applied monoamines and acetylcholine. Investigation was performed on 55 temperature-sensitive neurones (40 warm and 15 cold cells) and 18 temperature-insensitive ones.
2) 5-hydroxytryptamine had an excitatory effect on 11 out of 22 warm cells and caused a depression of firing rate in 2 out of 8 cold cells.
3) Reduction of activity following noradrenaline administration was observed in 6 out of 20 warm cells, while in the cold cells 3 out of 10 had an increased discharge rate.
4) Acetylcholine produced either a decrease or an increase in activity of warm cells and cold cells, but depression was predominant.
5) About one-third of temperature-sensitive neurones did not respond to any drugs.
6) Interspike interval histograms of spike trains recorded during the thermally steady state of brain showed gamma distribution in most of the responsive cells responding to monoamines and acetylcholine.

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To investigate the mechanism of desensitization to carbachol (Carb) in smooth muscle, the effects of prolonged applications of Carb on the electrical and mechanical properties of the guinea pig taenia coli were examined by either the microelectrode method or the double sucrose gap method.
1. Prolonged application of Carb (10^-5 g/ml; 5.5×10^-5 M) initially depolarized the membrane, reduced the membrane resistance and evoked contracture. These responses did not, however, continue but a desensitization to Carb then developed, i. e. the membrane was gradually repolarized, membrane resistance increased, and the muscle relaxed in spite of the presence of Carb.
2. During the repolarization phase in the presence of Carb (10^-5 g/ml), repeated current pulses transiently produced larger electrotonic potentials than those expected from the electrical displacement of the membrane potential. This transient increase of the membrane resistance was not directly related to the desensitization and it might be accounted for by a reduction of K permeability in the extrareceptor region at the depolarized condition.
3. Desensitization was accelerated in modified Krebs solutions with reduced Na or excess Ca, but was suppressed in solutions either with reduced Ca, or with reduced Cl or with excess K.
4. Procaine (27×10^-5 g/ml; 1 mM) supPressed both the depolarization and the desensitization induced by Carb. Hypertonic Krebs solution also suppressed the action of Carb on the taenia coli.
5. The contrast between the actions of Carb on the taenia coli and frog motor endplate has been discussed in terms of the ionic mechanisms involved.

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In order to reexamine the cortical distribution of the callosal connection, as well as its topographical relation to the binocular area in the rabbit visual cortex, the distribution of cortical responses evoked by electrical stimulation of the optic nerve and by direct cortical stimulation of the opposite visual area were studied in thirty immobilized animals.
1. The early response to ipsilateral optic nerve stimulation was similar in latency and waveform to that of the contralateral stimulation, and the area giving this response was determined as the binocular area. The binocular area which was a band of 6-7mm wide extended from the anteromedial to the posterolateral portion across the visual cortex.
2. Besides the early response, the binocular area showed the later response to ipsilateral optic nerve stimulation. The later response was found to be mediated via the corpus callosum, because it was abolished by cooling the opposited visual cortex. The interval between the beginning of the early and late responses was comparable with the latency of the transcallosal response elicited by direct cortical stimulation. The transcallosal response was also abolished permanently by cutting the posterior half of the corpus callosum. The area of transcallosal response and the area effective in eliciting this response were found to be in good agreement with each other and with the binocular area.
3. The callosal connection between the two binocular areas was not necessarily homotopic. For diffusely distributed points of stimulation in the binocular area of one cortex the points showing the maximal callosal responses in the other cortex were arranged in a narrow band in the middle of the binocular area. This band, about 1mm wide and running obliquely about 45 degrees to the midline, seemed to correspond to the projection line of the vertical meridian (decussation line) determined by Thompson et al.
These results suggest that the whole binocular area of both hemispheres in the rabbit are interconnected via the corpus callosum, and that the callosal fibers from the binocular area of one cortex terminate most densely in the middle of the opposite binocular area.

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1. Recent evidence suggests that the pancreatic digestive enzymes are secreted not only into the digestive tract via the gland lumen (exocrine), but also into the blood stream (endocrine). This dual secretion has been designated the ‘exocrine-endocrine partition’ of enzymes and their precursors, and was investigated in both the isolated and perfused rat pancreas, and the rat pancreas in situ.
2. The release of amylase was accompanied by the release of precursors of proteolytic enzymes either into the common duct or into the portal vein, and it was measured as a representation of release of pancreatic enzymes.
3. When the isolated pancreas was perfused with Krebs-Henseleit solution containing pancreozymin 0.2u./ml, the amylase output into the common duct was markedly increased, whereas the output into the vein was slightly increased. When the concentration of pancreozymin was increased up to 1.5u./ml, the output into the vein was markedly increased in contrast to a small increase in the output into duct.
4. Corresponding with the increase in output into the vein, acinar cells exhibiting high effective membrane resistances increased in number during perfusion of pancreozymin at a high concentration.
5. Enhanced release due to pancreozymin into the vein and into the duct was negated when calcium was omitted from the perfusing medium.
6. As a high dose of pancreozymin was injected repeatedly into the rat in situ, the blood concentration of amylase became higher but the increase in the output into the common duct became lower.
7. It is concluded that pancreatic enzymes and precursors preserved in zymogen granules may be extruded into the acinar lumen by the common calcium-dependent cellular processes; then, some of the secretory products may leak into the portal vein via enlarged intercellular spaces when a high concentration of pancreozymin is present.

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1. The effects of stimulation of the peripheral ends of the splanchnic nerve have been studied in isolated toad liver.
2. An increase in glucose concentration in perfusate in response to splanchnic nerve stimulation as well as adrenaline or noradrenaline application was observed.
3. Relationship between stimulus frequency and release of glucose was studied. From the experiments it was found that the amount of glucose released from the liver is closely related to the number of electrical pulses applied to the nerve.
4. Perfusate accumulated during splanchnic nerve stimulation in an isolated liver preparation showed a vasoconstrictor effect on blood vessels in the rabbit ear. Perfusate accumulated from reserpinized toad liver showed no vasoconstrictor effect.
5. Reserpine blocked the effect of nerve stimulation on release of glucose but not that of adrenaline application. Propranolol blocked the effect of stimulation as well as that of adrenaline injection. Dibenamine showed no blocking effect.
6. It is concluded that without vagal influence the release of glucose occurs in the liver as the result of splanchnic nerve stimulation via the hepatic innervation in toad.

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Histochemical and physiological properties of M. digastricus and M. semitendinosus of the guinea pig were investigated and compared since both muscle tissues have a red colour.
1) Action potential (overshoot potential; 14.9 mV) and membrane potential (-82.4 mV) recorded for M. digastricus were nearly the same as those obtained for M. semitendinosus (11.0 mV and -81.5 mV, respectively).
2) Both muscles generated twitch tension upon electrical stimulation; duration of tension was, however, much shorter in M. digastricus (42 msec at 35°C) than in M. semitendinosus (280 msec at 35°C). Active state of the mechanical response measured by the quick-release method also elucidated similar properties.
3) In the presence of various foreign anions (Br^-, NO₃^- and SCN^-), mechanical response of M. digastricus and M. semitendinosus were potentiated without any change of the membrane potential.
4) The critical membrane potentials for triggering K-induced contracture were -42 mV (70. 3mM K) in M. digastricus and -64 mV (26.7 mM K) in M. semitendinosus. These critical membrane potentials were lowered in Br^-- and NO₃^-- Krebs solutions.
5) In both muscles the maximum slopes of the membrane depolarization produced by tenfold changes of [K]₀ in various anions (NO₃^- and Br^-) were the same as those observed in the presence of Cl^-, but the slope became steeper in the presence of SCN^-.
6) In M. digastricus, caffeine (1-5 mM) potentiated twitch tension. In a 20 mM concentration of caffeine, contracture was produced. A 0.5 mM concentration of thymol potentiated the mechanical response, produced contracture and depolarized the membrane. In M. semitendinosus, caffeine showed more marked effects than those observed in M. digastricus.

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The action potentials of the atrial, ventricular and sinoatrial pacemaker cells of the golden carp were recorded by means of a microelectrode technique. Acetylcholine (10^-6g/ml) decreased the slope of the diastolic depolarization of the pacemaker cells. It shortened the action potential duration and caused the hyperpolarization of the atrial fibers. Ventricular fibers are insensitive to acetylcholine. Adrenaline (10^-6g/ml) increased the slope of the diastolic depolarization of the pacemaker cells. It increased the amplitude of the plateau phase of both the atrial and ventricular fibers and prolonged their action potential duration. In the atrial fibers the acetylcholine effect was blocked by atropine, while the adrenaline effect was blocked by propranolol, but not by phenoxybenzamine. The pacemaker cells were more resistant to tetrodotoxin than the atrial fibers, while the reverse was true for manganese ions. These results indicate that the action potentials of the myocardial cells of the golden carp are similar to those of mammals or amphibians.

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