ACUTE CHLORIDE DEPLETION ALKALOSIS: EFFECT OF ANIONS ON ITS MAINTENANCE AND CORRECTION

Dogs were made alkalotic and hypochloremic by peritoneal dialysis using an isoosmotic, chloride-free, bicarbonate-rich solution. No potassium deficit was induced by the procedure. Following dialysis, the animals voided large quantities of bicarbonate, sodium, and potassium with partial correction of alkalosis. Subsequently chloride was restricted while sodium and potassium were given as phosphate or sulfate. Plasma bicarbonate rose by 4 mEq/liter while renal excretion of acid increased slightly above control values and sodium was retained. Upon readministration of chloride, retention of chloride and potassium was associated with prompt correction of alkalosis. Chloride space returned to control values while renal excretion of acid did not change. In two experiments, chloride replacement was undertaken during potassium restriction. Again prompt correction of alkalosis was observed while potassium deficit remained unchanged. Renal excretion of acid decreased moderately. The data suggest that the renal tubules are limited in their capacity to reabsorb bicarbonate following acute chloride depletion alkalosis. The administration of impermeant anions favors the maintenance and progression of alkalosis. In the absence of significant reduction in renal excretion of acid, re-expansion of extracellular compartment could be viewed as an important factor in the correction of alkalosis.

EFFECTS PRODUCED ON INHIBITORY POSTSYNAPTIC POTENTIALS BY THE COUPLED INJECTIONS OF CATIONS AND ANIONS INTO MOTONEURONS

Ions have been injected into cat motoneurons impaled by a double microelectrode. Current has been passed down one barrel and up the other, so injecting cations out of the former and anions out of the latter. The injection of (K + + Cl - ) ions gave a depolarizing shift of the E IPSP almost as large as for a Cl - ion injection, and with a time course comparable with that for injections of Cl - or K + ions alone. The injection of (Na + + Cl - ) ions displaced the E IPSP by much the same amount and again the recovery time was almost as fast as after a Cl - ion injection, and much faster than after the injection of Na + ions alone. On the other hand injection of (2Na + + SO 2 4 - ions caused a slight displacement of the E IPSP in the hyperpolarizing direction. It was postulated that, when (K + ) i is depleted, there is an accelerated operation of an inward pump for (K + + Cl - ) ions with the consequence that the decline of high (Cl - ) i is slowed by a factor of three or more. The ion injection procedures did not provide evidence for or against the participation of K + ion movements in the generation of the IPSP , but this participation at a level comparable with that of Cl - ions had to be postulated in order to account for the normal hyperpolarizing character of the IPSP .

POTASSIUM-40 CONTENT AS A BASIS FOR THE CALCULATION OF BODY CELL MASS IN MAN

On the assumption that the potassium content of the body cell mass is constant it should be possible to estimate body cell mass by measuring potassium-40 activity with a whole-body scintillation counter. Relations of body cell mass to weight, lean body mass, and total body water are demonstrated.

STUDIES ON THE PATHOGENESIS OF FEVER. XII. ELECTROLYTIC FACTORYS INFLUENCING THE RELEASE OF ENDOGENOUS PYROGEN FROM POLYMORPHONUCLEAR LEUKOCYTES

The metabolic reactions responsible for the release of endogenous pyrogen from rabbit granulocytes incubated in 0.15 M NaCl are specifically inhibited by the presence of K⁺ (and by related alkali metal ions, Rb⁺ and Cs⁺) in the medium. The inhibitory action of K⁺ apparently involves penetration of the cell membrane and is directly antagonized by the cardiac glycoside, ouabain. It is concluded, therefore, that the inhibition of pyrogen release by extracellular K⁺ is due to transport of K⁺ into the cell. Although the precise molecular mechanisms which are responsible for the release of pyrogen from granulocytes incubated in K-free saline have not been elucidated, further study of the process has revealed: (a) that it is preceded by the accumulation of pyrogen within the cell, (b) that it depends upon the catalytic action of one or more sulfhydryl-containing enzymes, (c) that it does not require energy, either from glycolysis or from reactions depending on molecular oxygen, and (d) that its inhibition by K⁺ and by arsenite is qualitatively similar to the depression caused by these same reagents on the release of other leucocytic proteins; i.e., lysozyme and aldolase.

A STUDY OF EXTRACELLULAR SPACE IN CENTRAL NERVOUS TISSUE BY FREEZE-SUBSTITUTION

It was attempted to preserve the water distribution in central nervous tissue by rapid freezing followed by substitution fixation at low temperature. The vermis of the cerebellum of white mice was frozen by bringing it into contact with a polished silver mirror maintained at a temperature of about -207°C. The tissue was subjected to substitution fixation in acetone containing 2 per cent OsO₄ at -85°C for 2 days, and then prepared for electron microscopy by embedding in Maraglas, sectioning, and staining with lead citrate or uranyl acetate and lead. Cerebellum frozen within 30 seconds of circulatory arrest was compared with cerebellum frozen after 8 minutes' asphyxiation. From impedance measurements under these conditions, it could be expected that in the former tissue the electrolyte and water distribution is similar to that in the normal, oxygenated cerebellum, whereas in the asphyxiated tissue a transport of water and electrolytes into the intracellular compartment has taken place. Electron micrographs of tissue frozen shortly after circulatory arrest revealed the presence of an appreciable extracellular space between the axons of granular layer cells. Between glia, dendrites, and presynaptic endings the usual narrow clefts and even tight junctions were found. Also the synaptic cleft was of the usual width (250 to 300 A). In asphyxiated tissue, the extracellular space between the axons is either completely obliterated (tight junctions) or reduced to narrow clefts between apposing cell surfaces.

PROPAGATION OF ACTION POTENTIALS AND THE STRUCTURE OF THE NEXUS IN CARDIAC MUSCLE

The hypothesis that the nexus is a specialized structure allowing current flow between cell interiors is corroborated by concomitant structural changes of the nexus and changes of electrical coupling between cells due to soaking in solutions of abnormal tonicity. Fusiform frog atrial fibers are interconnected by nexuses. The nexuses, desmosomes, and regions of myofibrillar attachment of this muscle are not associated in a manner similar to intercalated discs of guinea pig cardiac muscle. Indeed, nexuses occur wherever cell membranes are closely apposed. Action potentials of frog atrial bundles detected extracellularly across a sucrose gap change from monophasic to diphasic when the gap is shunted by a resistor. This indicates that action potentials are transmitted across the gap when sufficient excitatory current is allowed to flow across the gap. When the sucrose solution in the gap is made hypertonic, propagation past the gap is blocked and the resistance between the cells in the gap increases. Electron micrographs demonstrate that the nexuses of frog atrium and guinea pig ventricle are ruptured by hypertonic solutions.

AN ANALYSIS OF FACTORS AFFECTING TISSUE OXYGEN TENSION

A mathematical analysis of the factors affecting the distribution of oxygen in living tissue is the subject of this paper. The Erlang -Krogh equation discussed in § 1 is derived from a highly simplified model, comprising a long, straight capillary surrounded by a cylinder of respiring tissue. Succeeding sections describe the effects upon the distribution of oxygen as predicted by this model of the following factors: ( a ) Hexagonal rather than cylindrical symmetry. ( b ) Decrease in the rate of consumption of oxygen by the cells in the tissue when the oxygen tension falls below a certain value. ( c ) Variation of the diffusion constant with position in the tissue. ( d ) A sudden change in the value of the oxygen tension at the capillary surface. ( e ) A decrease in oxygen tension along the length of the capillary. ( f ) Fluid flow in the extracellular fluid.

ESTIMATION OF EXTRACELLULAR SPACES OF SMOOTH MUSCLE USING DIFFERENT-SIZED MOLECULES

The apparent fraction of tissue water available as solvent was determined for a number of test substances: urea, arabinose, mannitol, sucrose, raffinose, inulin, and radioiodinated serum albumin. The apparent extracellular spaces decrease with increasing molecular size. Urea seems to come to concentration equilibrium in all tissue water. Arabinose and mannitol values are close together at about 70% tissue water. Similarly sucrose, raffinose, and inulin values cluster at about 48% tissue water, while RISA can reach only about 20%. The amounts of sodium, potassium, and chloride in canine intestinal smooth muscle are similar to values given for other smooth muscle. Intracellular ion concentrations similar to those of other tissues can be calculated if the true extracellular space is between that measured by RISA and sucrose.

EFFECTS OF ANAPHYLAXIS IN VIVO ON THE LIPID AND PROTEIN CONTENT OF GUINEA-PIG SERUM AND EXTRACELLULAR FLUID OF LUNG TISSUE

Determinations of total cholesterol, phospholipid and glyceride in serum samples obtained from guinea-pigs by cardiac puncture before and after anaphylaxis in vivo indicated reductions occurred in all three fractions after anaphylactic shock. The fall in glyceride was preceded by a rise. Anaphylaxis also induced an accumulation of lipid in oedema fluid in the lungs. These changes were reduced in animals protected from anaphylaxis by pretreatment with a combination of mepyramine and ethanolamine or mepyramine and hydrocortisone.