scholarly journals Phorbol esters and horseradish peroxidase stimulate pinocytosis and redirect the flow of pinocytosed fluid in macrophages.

1985 ◽  
Vol 100 (3) ◽  
pp. 851-859 ◽  
Author(s):  
J A Swanson ◽  
B D Yirinec ◽  
S C Silverstein
Keyword(s):  
Steady State ◽  
Horseradish Peroxidase ◽  
Phorbol Esters ◽  
Lucifer Yellow ◽  
Fluid Phase ◽  
Peritoneal Macrophages ◽  
Tumor Promoter ◽  
Steady State Rate ◽  
Reduced Rate ◽  
Rate Of Accumulation

Lucifer Yellow CH (LY) is an excellent probe for fluid-phase pinocytosis. It accumulates within the macrophage vacuolar system, is not degraded, and is not toxic at concentrations of 6.0 mg/ml. Its uptake is inhibited at 0 degree C. Thioglycollate-elicited mouse peritoneal macrophages were found to exhibit curvilinear uptake kinetics of LY. Upon addition of LY to the medium, there was a brief period of very rapid cellular accumulation of the dye (1,400 ng of LY/mg protein per h at 1 mg/ml LY). This rate of accumulation most closely approximates the rate of fluid influx by pinocytosis. Within 60 min, the rate of LY accumulation slowed to a steady-state rate of 250 ng/mg protein per h which then continued for up to 18 h. Pulse-chase experiments revealed that the reduced rate of accumulation under steady-state conditions was due to efflux of LY. Only 20% of LY taken into the cells was retained; the remainder was released back into the medium. Efflux has two components, rapid and slow; each can be characterized kinetically as a first-order reaction. The kinetics are similar to those described by Besterman et al. (Besterman, J. M., J. A. Airhart, R. C. Woodworth, and R. B. Low, 1981, J. Cell Biol. 91:716-727) who interpret fluid-phase pinocytosis as involving at least two compartments, one small, rapidly turning over compartment and another apparently larger one which fills and empties slowly. To search for processes that control intracellular fluid traffic, we studied pinocytosis after treatment of macrophages with horseradish peroxidase (HRP) or with the tumor promoter phorbol myristate acetate (PMA). HRP, often used as a marker for fluid-phase pinocytosis, was observed to stimulate the rate of LY accumulation in macrophages. PMA caused an immediate four- to sevenfold increase in the rate of LY accumulation. Both HRP and PMA increased LY accumulation by stimulating influx and reducing the percentage of internalized fluid that is rapidly recycled. A greater proportion of endocytosed fluid passes into the slowly emptying compartment (presumed lysosomes). These experiments demonstrate that because of the considerable efflux by cells, measurement of marker accumulation inaccurately estimates the rate of fluid pinocytosis. Moreover, pinocytic flow of water and solutes through cytoplasm is subject to regulation at points beyond the formation of pinosomes.

Effects of colchicine on endocytosis of horseradish peroxidase by rat peritoneal macrophages

1980 ◽  
Vol 45 (1) ◽  
pp. 59-71 ◽  
Author(s):  
A. Piasek ◽  
J. Thyberg
Keyword(s):  
Horseradish Peroxidase ◽  
Digestive Enzymes ◽  
Cytochalasin B ◽  
Fluid Phase ◽  
Peritoneal Macrophages ◽  
The Other ◽  
Fluid Phase Endocytosis ◽  
Cytoplasmic Microtubules ◽  
Endocytic Vesicles ◽  
Cytoplasmic Complex

Horseradish peroxidase (HRP) was used as an exogenous marker to study the effects of microtubule-disruptive drugs on endocytosis in cultures of thioglycollate-elicited rat peritoneal macrophages. Colchicine and vinblastine, but not lumicolchicine or cytochalasin B, reduced HRP uptake by about 30–40%. However, as determined by stereological measurements, the size of the HRP-containing compartment within the cells remained unaltered. In both control cells and cells treated with colchicine or vinblastine the HRP-reactive vesicles were preferentially located close to the dictyosomes (stacks of cisternae) despite the fact that the Golgi complex was disorganized in the treated cells. These results suggest that intact cytoplasmic complex was disorganized in the treated cells. These results suggest that intact cytoplasmic microtubules are required to maintain a normal rate of fluid phase endocytosis in macrophages. On the other hand, it seems as if microtubules are not necessary for the translocation of newly formed endocytic vesicles/lysosomes to the dictyosomes, from which they probably are supplied with digestive enzymes.

scholarly journals Tubular lysosomes accompany stimulated pinocytosis in macrophages.

1987 ◽  
Vol 104 (5) ◽  
pp. 1217-1222 ◽  
Author(s):  
J Swanson ◽  
E Burke ◽  
S C Silverstein
Keyword(s):  
Phorbol Ester ◽  
Lucifer Yellow ◽  
Fluid Phase ◽  
Peritoneal Macrophages ◽  
Latex Beads ◽  
Solute Accumulation ◽  
Cytoplasmic Microtubules ◽  
Macrophage Stimulation ◽  
Mouse Peritoneal Macrophages ◽  
In Cells

A network of tubular lysosomes extends through the cytoplasm of J774.2 macrophages and phorbol ester-treated mouse peritoneal macrophages. The presence of this network is dependent upon the integrity of cytoplasmic microtubules and correlates with high cellular rates of accumulation of Lucifer Yellow (LY), a marker of fluid phase pinocytosis. We tested the hypothesis that the efficiency of LY transfer between the pinosomal and lysosomal compartments is increased in the presence of tubular lysosomes by asking how conditions that deplete the tubular lysosome network affect pinocytic accumulation of LY. Tubular lysosomes were disassembled in cells treated with microtubule-depolymerizing drugs or in cells that had phagocytosed latex beads. In unstimulated peritoneal macrophages, which normally contain few tubular lysosomes and which exhibit relatively inefficient transfer of pinocytosed LY to lysosomes, such treatments had little effect on pinocytosis. However, in J774 macrophages and phorbol ester-stimulated peritoneal macrophages, these treatments markedly reduced the efficiency of pinocytic accumulation of LY. We conclude that a basal level of solute accumulation via pinocytosis proceeds independently of the tubular lysosomes, and that an extended tubular lysosomal network contributes to the elevated rates of solute accumulation that accompany macrophage stimulation. Moreover, we suggest that the transformed mouse macrophage cell line J774 exhibits this stimulated pinocytosis constitutively.

Trafficking of interleukin 2 and transferrin in endosomal fractions of T lymphocytes

1994 ◽  
Vol 107 (5) ◽  
pp. 1289-1295 ◽  
Author(s):  
V. Duprez ◽  
M. Smoljanovic ◽  
M. Lieb ◽  
A. Dautry-Varsat
Keyword(s):  
Horseradish Peroxidase ◽  
Interleukin 2 ◽  
Fluid Phase ◽  
Endocytic Pathway ◽  
Recycling Endosomes ◽  
High Affinity ◽  
Human T Cell ◽  
Late Endosomes ◽  
Discontinuous Sucrose Gradient ◽  
Acidic Organelles

The T lymphocyte growth factor interleukin 2 binds to surface high-affinity receptors and is rapidly internalized and degraded in acidic organelles. The alpha and beta chains of high-affinity interleukin 2 receptors are internalized together with interleukin 2. To identify the intracellular pathway followed by interleukin 2, we have compared the subcellular distribution of interleukin 2, transferrin and a fluid-phase marker, horseradish peroxidase, in the human T cell line IARC 301.5. Transferrin was used as a marker of early and recycling endosomes, and horseradish peroxidase to probe for the whole endocytic pathway. Fractionation of intracellular organelles on a discontinuous sucrose gradient showed that internalized interleukin 2 is initially mostly found in compartments with similar densities to transferrin, e.g. early and recycling endosomes. The kinetics of entry and exit of interleukin 2 from such organelles was much slower than that of transferrin. Later on, interleukin 2 is predominantly found in dense lysosome-containing fractions. Very little, if any, interleukin 2 was found in fractions corresponding to late endosomes containing horseradish peroxidase. These results suggest that, after endocytosis, interleukin 2 enters early or recycling endosomes before it reaches dense lysosomes.

Resting Membrane Properties of Locust Muscle and Their Modulation I. Actions of the Neuropeptides YGGFMRFamide and Proctolin

1998 ◽  
Vol 80 (2) ◽  
pp. 771-784 ◽  
Author(s):  
Christian Walther ◽  
Klaus E. Zittlau ◽  
Harald Murck ◽  
Karlheinz Voigt
Keyword(s):  
Steady State ◽  
Phorbol Esters ◽  
Biological Significance ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
Voltage Sensitivity ◽  
Locust Muscle ◽  
Current Voltage ◽  
Instantaneous Current ◽  
Electrode Voltage

Walther, Christian, Klaus E. Zittlau, Harald Murck, and Karlheinz Voigt. Resting membrane properties of locust muscle and their modulation. I. Actions of the neuropeptides YGGFMRFamide and proctolin. J. Neurophysiol. 80: 771–784, 1998. The resting K+ conductance ( G K,r) of locust jumping muscle and its modulation by two neuropeptides, proctolin (Arg-Tyr-Leu-Pro-Thr) and YGGFMRFamide (Tyr-Gly-Gly-Phe-Met-Arg-Phe-NH2), were investigated using the two-electrode voltage clamp. At a physiological [K+]o of 10 mM, G K,r accounts for ∼90% of the membrane resting conductance, and the resting membrane potential differs by ≤1 mV from E K (mean: −74 mV). There is a K+ conductance that slowly activates on hyperpolarization ( G K,H) and that seems to be largely located in the transverse tubules. Steady-state activation of G K,H was analyzed by tail current measurements. G K,H is activated partially at E K but accounts for probably ≤50% of total resting K+ conductance. Raising [K+]o caused a large increase in G K,r and in maximal steady state G K,H without shifting the voltage sensitivity of G K,H. YGGFMRFamide and proctolin reduce G K,H, mainly affecting the maximal steady-state conductance. The voltage-insensitive component of the resting K+ conductance is also reduced. The conductance suppressed by the peptides exhibited an outwardly rectifying instantaneous current/voltage-characteristic that is quite similar to that of G K,H. The actions of the two peptides appeared to be identical, but proctolin was by some two orders of magnitude more potent than YGGFMRFamide. The effects of both peptides are mediated by G proteins. They are mimicked by phorbol esters but do not seem to be initiated by either branch of the phospholipase C-dependent intracellular pathways. The properties of the resting K+ conductance in locust muscle and other invertebrate muscles are compared. The biological significance of peptide-induced reduction in resting K+ conductance is discussed in view of the known property of proctolin to support tonic force as opposed to FMRFamide-peptides that support quick leg movements.

Corticosterone secretion in rats as a function of ACTH input and adrenal blood flow

1965 ◽  
Vol 209 (4) ◽  
pp. 811-814 ◽  
Author(s):  
John C. Porter ◽  
M. S. Klaiber
Keyword(s):  
Blood Flow ◽  
Steady State ◽  
Steady Increase ◽  
Constant Input ◽  
Corticosterone Secretion ◽  
Steady State Rate ◽  
State Rate

The rate of secretion of corticosterone from the left adrenal of rats receiving a constant input of ACTH was determined for different flows of blood through the adrenal during the 2- to 3-hr interval following hypophysectomy. Two hours after hypophysectomy the secretion of corticosterone was low in all groups regardless of flow. An input of 0.26 mU ACTH/min caused a steady increase in secretion for 30–40 min before a steady-state rate was attained. The average steady-state rate of secretion was 1.1, 2.4, 3.5, 6.2, 7.2, 6.2, and 6.2 µg/5 min for flows of 0.005, 0.012, 0.023, 0.034, 0.039, 0.051, and 0.058 ml/min, respectively. Under the conditions of these experiments where the input of ACTH was 0.26 mU/min the secretion of corticosterone increased significantly with time of input of ACTH and with flow of blood through the adrenal.

scholarly journals The Natural Rate of Interest and the Optimal Rate of Interest in the Steady State

2021 ◽  
pp. 17-41
Author(s):  
Carl Christian von Weizsäcker ◽  
Hagen M. Krämer
Keyword(s):  
Steady State ◽  
Public Debt ◽  
Fundamental Equation ◽  
Optimal Rate ◽  
Natural Rate ◽  
Real Rate ◽  
Capital Theory ◽  
Steady State Rate ◽  
Natural Rate Of Interest ◽  
State Rate

AbstractThe “natural rate of interest” is the hypothetical, risk-free real rate of interest that would obtain in a closed economy, if net public debt were zero. It is considerably less than the optimal steady-state rate of interest, which is equal to the system’s growth rate. This holds for a very general “meta-model.” The fundamental equation of capital theory holds on the optimal steady-state path: T = Z − D, where T is the overall economic period of production, Z is the representative private “waiting period” of consumers and D is the public debt ratio. Prosperity is at least 30% lower at the natural rate of interest than at the optimal rate.

scholarly journals c-fos gene transcription in murine macrophages is modulated by a calcium-dependent block to elongation in intron 1

1991 ◽  
Vol 11 (5) ◽  
pp. 2826-2831
Author(s):  
M A Collart ◽  
N Tourkine ◽  
D Belin ◽  
P Vassalli ◽  
P Jeanteur ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Gene Transcription ◽  
Peritoneal Macrophages ◽  
Tumor Promoter ◽  
Transcriptional Elongation ◽  
Myristate Acetate ◽  
Transcriptional Initiation ◽  
Calcium Dependent ◽  
Intron 1 ◽  
Responsive Element

Cultured mouse thioglycolate-elicited peritoneal macrophages exhibit a strong block to transcriptional elongation beyond the end of the c-fos gene first exon. This block is absent in freshly isolated peritoneal cells, appears slowly during culture, and does not require adherence of the cells. The extent of this block is largely responsible for the levels of c-fos mRNA in cultured macrophages, even after modulation by agents such as the tumor promoter phorbol myristate acetate and increased intracellular cyclic AMP, which also increase the activity of the c-fos promoter. When macrophages are cultured in the absence of mobilizable calcium, the block can no longer be relieved by any inducing agent. Conversely, upon calcium influxes, there is little alteration in the level of transcriptional initiation, but transcription proceeds efficiently through the entire c-fos locus. These results suggest the presence of an intragenic calcium-responsive element in the c-fos gene and illustrate its key role in the control of c-fos gene transcription.

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