摘要:

AbstractImpulse discharges in the chorda tympani nerve of rats to stimulation of the tongue by NaCl, KCl, CaCl2, HCl, quinine and sucrose at varying temperatures were recorded using an integrator. The tongue had been preadapted to temperature of stimulating solutions so as to eliminate thermal response. The magnitude of response to all kinds of stimuli except for sodium salts of 0.01 to 0.03 M was increased with a rise in temperature from 10° to 30°C and declined from 30° to 45°C, indicating the greatest magnitude at about 30°C. The response magnitude for 0.01 M NaCl was decreased with a rise in temperature from 10° to 45°C. The threshold for NaCl rises with a rise in temperature. Q10values for the magnitude of response to 0.03 M to 1.0 M NaCl, KCl, CaCl2, HCl, quinine and sucrose are less than two between 10° and 30°C, −1.1 to −1.9 between 30° to 40°C and −1.8 to −3.4 between 35° and 45°C. Sucrose, HCl and quinine gave greater Q10values than did NaCl, KCl and CaCl2. From such small Q10values it has been concluded that the reaction between taste receptors and stimuli, which ultimately leads to initiation of gustatory impulses, is of physical nature rathe

ISSN:0095-9898    

DOI:10.1002/jcp.1030660102

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractThe sympathetic ganglion of the toad consists of two kinds of neurons, the sB and sC neurons of which axons are the B and C fibers, respectively. The sB neurons receive a monosegmental innervation of preganglionic B fibers whereas the sC neurons receive mono‐ or multisegmental innervation of preganglionic C fibers. The pre‐ and postganglionic neurons are divided into a fast (sB neuron) and slow (sC neuron) conduction system. The conduction velocity of the preganglionic axons is proportional to that of the synaptically connected postganglionic neuron axons in the sB and sC neuron systems. In the sB neuron system, the conduction velocity of the preganglionic axons is faster than that of the postganglionic fibers. The relation is reversed in the sC neuron system. The antidromic and orthodromic responses as well as the electrical membrane properties of sC neurons were analyzed and compared with those of the sB neurons. In both neurons, the time constant of the synaptic potential decay was always longer than that of the membrane. The synaptic potentials of sB and sC neurons were abolished at the membrane potential levels of −10 mv and −7 mv on the average, respectively, which indicates that the equilibrium potentials of these neurons are almost the same. The changes in the excitability of the soma as well as axon of the sB and sC neurons after a single response and the response of the sB and sC neurons to a long cathodal current were analyzed and c

ISSN:0095-9898    

DOI:10.1002/jcp.1030660103

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractSusceptible monkey kidney cultures were infected with SV40. DNA alterations were studied in stained preparations and by quantitative cytophotometry. Early changes included a decrease in mitotic rate. Later, enlarged DNA granules formed at the nuclear membrane, followed by massive production of refractile inclusion particles of DNA in the nuclear interior. This heavily stained mass often included separate, larger DNA viral bodies surrounded by halos. Also present within this mass was a hypertrophied nucleolus enveloped by an intense ring of DNA and a halo. Prominent DNA granules were observed within nucleoli. Strands of DNA passed between the mass of inclusion particles and the nucleolar‐associated DNA and nucleolus. Nuclei with inclusions contained increased DNA in well‐developed cases which was at least five times that found in normal cells. Two types of abnormal nuclei were observed, one of which was large, appeared early, and contained inclusions (Stage 1), while the other appeared later and was pyknotic (Stage 2). It is suggested that SV40 induces arrest of the cell cycle in the G2 phase which causes a decreased mitotic rate and a scarcity of infected nuclei in the euploid DNA cl

ISSN:0095-9898    

DOI:10.1002/jcp.1030660104

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractPig red cells were characterized structurally and chemically, the rates of certain of their carbohydrate metabolic pathways were determined, the capacity to utilize these pathways for methemoglobin reduction was measured, and the results were compared with similar studies in human erythrocytes. Pig cells are smaller, contain less hemoglobin but are similar to human cells in mean cellular hemoglobin concentration. Unlike most other mammalian red cells, including human erythrocytes, pig cells are glucose “free” or nearly so; plasma concentrations of glucose are similar in both species. On a per cell basis, the content of adenosine triphosphate and reduced glutathione is similar in both species. Pig red cells catabolize glucose at about one‐tenth the human rate; for each mole of glucose consumed, two moles of lactate are formed. In both species, a similarproportion(5 to 10%) of the total glucose catabolized passes via the phosphogluconate oxidative pathway. Both species form lactate from inosine at similar rates; the pathways involved appear similar. Pig hemolysates prepared in water form lactate from glucose, glucose‐6‐phosphate, or inosine; freeze‐thawing destroys this potential. Methemoglobin reduction rates of red cells suspended in plasma are similar in both species. With human cells the plasma glucose concentration accounts for the rate; with pig cells, the lactate level appears responsible. Cells of both species apparently link methemoglobin reduction to reduced diphosphopyridine nucleotide generated via Embden‐Meyerhof glycolysis but can couple reduced triphosphopyridine nucleotide, generated via the phosphogluconate oxidative pathway, to methemoglobin redu

ISSN:0095-9898    

DOI:10.1002/jcp.1030660105

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractRat liver cell microsomes were subfractionated in D2O‐sucrose solutions of various densities into three subfractions with densities>1.23, 1.18–1.23 and 1.12–1.18. There was an inverse correlation between the nucleic acid and lipid contents of these subfractions; the highest density subfraction had a relatively high nucleic acid (20.9%) and low lipid (15.1%) content and the lowest density subfraction had a low nucleic acid (3.4%) and a high lipid (45.2%) content. Whole microsomes were determined to be composed of 55.0% protein, 8.6% nucleic acid and 36.4% lipid. This composition of microsomes was calculated to reflect a nucleoprotein and lipoprotein content of 28% and 72%, respectively. Investigation of Ca and Mg binding by the three microsome subfractions and by the whole microsome fraction after equilibration for 12 hours in a medium of pH 6.7 containing 8–9 meq Ca or Mg/liter indicated that all fractions retained considerable amounts of the divalent cations (1.5–2.6 meq/g N). The nucleoprotein fraction was calculated to bind 0.35–0.40 meq Ca or Mg/g dry weight of nucleoprotein and the lipoprotein fraction 0.12 meq Ca or Mg/g dry weight of lipoprotein. Nevertheless, the lipoprotein fraction of microsomes is responsible for 45% of the total binding of Ca or Mg by the whole microsome fraction. These observations support the contention that cellular membrane structures, composed essentially of lipoprotein, can bind considerable quantities of the dival

ISSN:0095-9898    

DOI:10.1002/jcp.1030660106

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractStudies of the effect of triton X‐100 on the fragility of rabbit erythrocytes and on shape and volume changes of rabbit and sheep erythrocytes suspended in an isotonic salt solution suggest that this subtance alters the erythrocytes of other species in a manner similar to that reported previously for human red cells. Using a densimeter technique it was found that the permeability of relatively slowly moving non‐electrolyte‐carrier‐complexes is decreased by triton X‐100 but more rapidly penetrating systems are not affected by this substance. The permeability of some molecules which cross the membrane by diffusion is increased by triton X‐100. It is suggested that triton X‐100 affects both the aqueous channels and the portion of the membrane across which carriers move. Its action is less than that of tannic ac

ISSN:0095-9898    

DOI:10.1002/jcp.1030660107

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractThe glycolytic enzymes, lactic dehydrogenase and aldolase, usually thought to be freely dissolved in the sarcoplasmic matrix, are in good part attached to the muscle ultrastructure. This attachment becomes manifest when the enzyme activities and specific activities of the press juices of whole skeletal muscles (rabbit) are compared with those of minced muscles, all obtained by ultracentrifugation of the tissues at 40,000 xpm for 16 to 20 hours. Mincing causes a great increase in the activities, associated with a rise in the volume and protein concentration of the press juices. We interpret these increases to be due to the solution in the matrix of enzymes previously attached to the ultrastructure.The same conclusion is reached by a different method, which we call “washing the ultrastructure.” It consists in multiple centrifugations of whole skeletal muscles, and removal of press juices, alternating with periods of imbibition of a buffer (0.1 M phosphate at pH 7.5) too dilute to dissolve out the fibrous proteins. During the imbibitions enzymes diffuse out into the buffer not imbibed, which becomes an extract. After four centrifugation‐imbibition sequences in as many days nearly all of the fluid matrix has been replaced by buffer. Enzyme activities fall steeply in press juices and extracts until nearly all freely dissolved enzymes have been washed away. Homogenates of the pressed muscles then show activities which are about half of those found in the homogenates of unpressed control muscles. We conclude that the enzymes found in the homogenates of the pressed muscles have previously been attached to the ultrastructure.Similar experiments with heart muscle indicate that nearly all of these enzymes are normally attached to the ultrastructure. Press juices contain only traces of activity, even after the heart has been minced. A fraction of the enzymes is slowly detached during the centrifugation‐imbibition sequences, appearing mainly in the e

ISSN:0095-9898    

DOI:10.1002/jcp.1030660108

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractNormal and thyroidectomized rats were maintained on normal diets and on diets containing 0.3% N‐propylthiouracil. The normal rats on normal diets had significantly lower serum cholesterol levels than did any of the other groups. Liver cholesterol levels were elevated only in the thyroidectomized rats fed normal diet. The hypercholesteremic effect of N‐propylthiouracil observed in the thyroidectomized rats appears to be due to release of liver cholesterol.Liver mitochondrial preparations from all four groups of rats oxidized cholesterol‐26‐14C and sodium octanoate‐1‐14C to14CO2to the same extent. The data further support the hypothesis that the effect of thyroid on cholesterol degradation is mediated at the level of nuclear hy

ISSN:0095-9898    

DOI:10.1002/jcp.1030660109

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractWe have measured the equilibrium efflux of C14labeled glucose across the cell membrane of the human erythrocyte under conditions when glucose was present in equal concentrations on both sides of the cell membrane, and also the net efflux of C14labeled glucose from glucose‐loaded cells into a large extracellular environment that contained no glucose. A method of ultrafiltration through millipore filter discs was developed to obtain samples of medium during the loss of cell isotope to a medium free of isotope. Fluxes with half times as low as five seconds could be determined accurately and reproducibly. With this method we have extended the observations of other workers down to glucose concentrations of 0.03 M and found as others had previously that the half time for tracer exchange would decrease with a decrease in the equilibrium glucose concentrations. Further, by measuring equilibrium fluxes and maximal net fluxes of cells from the same blood sample, we have obtained evidence that the carrier laden with glucose is transported more rapidly than the free carrie

ISSN:0095-9898    

DOI:10.1002/jcp.1030660110

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY

摘要:

AbstractHomogenates of rat and frog liver were incubated with ThDP and ThMP at different pHs.The products of hydrolysis were identified by paper chromatography.In experiments carried out at pH 9 with ThDP as substrate in the presence of rat liver, the spot corresponding to Th did not appear on the chromatogram. This was in contrast with parallel experiments with frog liver. ThMP from commercial source behaved differently toward enzymatic decomposition than ThMP originating from hydrolysis of ThDP. Attempts have been made to explain these differences.

ISSN:0095-9898    

DOI:10.1002/jcp.1030660111

出版商:The Wistar Institute of Anatomy and Biology    

年代:1965

数据来源: WILEY