Paradoxical changes in PGE2 synthesis and responsiveness of the adenylate cyclase-linked prostaglandin receptor system in ‘post-mortem-stimulated’ and ‘steady state’ resident rat peritoneal macrophages

1984 ◽  
Vol 15 (1-2) ◽  
pp. 19-20 ◽  
Author(s):  
G. R. Elliott ◽  
M. J. P. Adolfs ◽  
I. L. Bonta
Keyword(s):  
Steady State ◽  
Adenylate Cyclase ◽  
Peritoneal Macrophages ◽  
Post Mortem ◽  
Receptor System ◽  
Pge2 Synthesis ◽  
Prostaglandin Receptor ◽  
State Resident

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.

scholarly journals Characterization of murine peritoneal macrophage receptors for fibrin(ogen) degradation products

Blood ◽  
1986 ◽  
Vol 67 (5) ◽  
pp. 1224-1228 ◽  
Author(s):  
S Rajagopalan ◽  
SV Pizzo
Keyword(s):  
Degradation Products ◽  
Peritoneal Macrophages ◽  
Receptor System ◽  
Human Fibrinogen ◽  
Murine Peritoneal Macrophage ◽  
High Affinity ◽  
Macrophage Receptors ◽  
Low Concentrations ◽  
Mouse Peritoneal Macrophages

Abstract The binding of human fibrinogen degradation fragments D1, E, X, and Y, as well as fibrin fragment D1 dimer, to mouse peritoneal macrophages was examined. A Scatchard plot of fragment D1 binding was biphasic, suggesting two classes of receptors. Fragments D1, D1 dimer, X, and Y in low concentrations bound to macrophages with high affinity (Kd = 23 to 73 X 10(-11) mol/L). Fragment E bound specifically but at a much lower level than the other fragments. Fragment D1 was able to compete for the binding of radiolabeled fragments X and Y but not radiolabeled fragment E. These studies indicate that fragments D and E are recognized by separate receptor systems but that all of the fibrinogen degradation products that contain the D domain are recognized by the same receptor system.

Effects of post-mortem delay on high affinity forskolin binding sites and adenylate cyclase activity in rat and human striatum and cerebral cortex

1993 ◽  
Vol 629 (2) ◽  
pp. 225-230 ◽  
Author(s):  
Brian Ross ◽  
Deborah Dawson ◽  
Deborah Dewar ◽  
Mhairi Macrae ◽  
John Knowler ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Adenylate Cyclase ◽  
Binding Sites ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Post Mortem ◽  
High Affinity

scholarly journals Characterization of murine peritoneal macrophage receptors for fibrin(ogen) degradation products

Blood ◽  
1986 ◽  
Vol 67 (5) ◽  
pp. 1224-1228 ◽  
Author(s):  
S Rajagopalan ◽  
SV Pizzo
Keyword(s):  
Degradation Products ◽  
Peritoneal Macrophages ◽  
Receptor System ◽  
Human Fibrinogen ◽  
Murine Peritoneal Macrophage ◽  
High Affinity ◽  
Macrophage Receptors ◽  
Low Concentrations ◽  
Mouse Peritoneal Macrophages

The binding of human fibrinogen degradation fragments D1, E, X, and Y, as well as fibrin fragment D1 dimer, to mouse peritoneal macrophages was examined. A Scatchard plot of fragment D1 binding was biphasic, suggesting two classes of receptors. Fragments D1, D1 dimer, X, and Y in low concentrations bound to macrophages with high affinity (Kd = 23 to 73 X 10(-11) mol/L). Fragment E bound specifically but at a much lower level than the other fragments. Fragment D1 was able to compete for the binding of radiolabeled fragments X and Y but not radiolabeled fragment E. These studies indicate that fragments D and E are recognized by separate receptor systems but that all of the fibrinogen degradation products that contain the D domain are recognized by the same receptor system.

Adenosine 5’-O-(2-Thiodiphosphate) (ADP-β-S) Is A Partial Agonist At The ADP Receptor Of Human Platelets

1981 ◽  
Author(s):  
N J Cusack ◽  
S M O Hourani
Keyword(s):  
Platelet Aggregation ◽  
Adenylate Cyclase ◽  
Human Platelet ◽  
Partial Agonist ◽  
Human Platelets ◽  
Simultaneous Addition ◽  
Prostaglandin Receptor ◽  
Human Platelet Aggregation ◽  
Adp Receptor ◽  
Stimulation Of

ADP induces human platelet aggregation and inhibits the stimulation of platelet adenylate cyclase by prostaglandin E1 (PGE1), but analogues of ADP in which the diphosphate group is modified retain only weak aggregating activity. However, ADP-β-S, an ADP analogue in which a terminal phosphate oxygen is replaced by sulphur, is known to be equipotent with ADP as an inhibitor of PGE1-stimulated adenylate cyclase in purified human platelet membranes. We therefore tested ADP-β-S on intact human platelets. ADP-β-S induced human platelet aggregation and inhibited PGE1-stimulated adenylate cyclase, but in botn cases was less potent than ADP and only achieved 75% and 50% respectively of the maximal effects of ADP. Aggregation induced by ADP-β-S was competitively inhibited by ATP (50 μM), a known ADP antagonist.Both these actions of ADP could be inhibited by the simultaneous addition of ADP-β-S (50 μM). Aggregation induced by a stable endoperoxide analogue (11 ,9 -epoxymethano PGH2), which acts at a prostaglandin receptor rather than at an ADP receptor, was not inhibited by the simultaneous addition of ADP-β-S (50 μM). The behaviour of ADP-β-S towards human platelets is therefore tnat of a partial agonist at the ADP receptor.

scholarly journals THE ORIGIN AND KINETICS OF MONONUCLEAR PHAGOCYTES

1968 ◽  
Vol 128 (3) ◽  
pp. 415-435 ◽  
Author(s):  
Ralph van Furth ◽  
Zanvil A. Cohn
Keyword(s):  
Bone Marrow ◽  
Steady State ◽  
Peripheral Blood ◽  
Mononuclear Cells ◽  
Calf Serum ◽  
Peritoneal Macrophages ◽  
Mononuclear Phagocytes ◽  
Sterile Inflammation

The origin and turnover of efferent populations of mouse mononuclear phagocytes has been described. Mononuclear phagocytes were defined as mononuclear cells which are able to adhere to glass and phagocytize. In vitro labeling studies with thymidine-3H showed that monocytes in the peripheral blood and peritoneal macrophages do not multiply and can be considered end cells in a normal, steady state situation. However, the mononuclear phagocytes of the bone marrow appear to be rapidly dividing cells. This conclusion was supported by in vivo labeling experiments. A peak of labeled mononuclear phagocytes of the bone marrow was found 24 hr after a pulse of thymidine-3H. This was followed, 24 hr later, by a peak of labeled monocytes in the peripheral blood. From these experiments it was concluded that the rapidly dividing mononuclear phagocytes of the bone marrow, called promonocytes, are the progenitor cells of the monocytes. Labeling studies after splenectomy and after X-irradiation excluded other organs as a major source of the monocytes. Peak labeling of both the blood monocyte and peritoneal macrophages occurred at the same time. A rapid entry of monocytes from the blood into the peritoneal cavity was observed, after a sterile inflammation was evoked by an injection of newborn calf serum. These data have led to the conclusion that monocytes give rise to peritoneal macrophages. No indications have been obtained that mononuclear phagocytes originate from lymphocytes. In the normal steady state the monocytes leave the circulation by a random process, with a half-time of 22 hr. The average blood transit time of the monocytes has been calculated to be 32 hr. The turnover rate of peritoneal macrophages was low and estimated at about 0.1% per hour. On the basis of these studies the life history of mouse mononuclear phagocytes was formulated to be: promonocytes in the bone marrow, → monocytes in the peripheral blood, → macrophages in the tissue.

Abstract 2165: Harvesting the Energy of Cardiac Motion to Power a Pacemaker

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Paul Roberts ◽  
Giles Stanley ◽  
John M Morgan
Keyword(s):  
Heart Rate ◽  
Steady State ◽  
Energy Harvesting ◽  
Internal Jugular Vein ◽  
Cardiac Cycle ◽  
Jugular Vein ◽  
Data Acquisition System ◽  
Cardiac Motion ◽  
Post Mortem ◽  
Surplus Energy

There is significant motion of the heart with each cardiac cycle. We examine the feasibility of harvesting surplus energy (HE) using a catheter-mounted device (CMD) that could be incorporated into a pacemaker/ICD lead and assist powering. The CMD consisted of a pacemaker electrode incorporating a coaxially mounted device with 2 pressure responsive bladders that utilise cardiac pressure (RV/RA) to drive a linear generator. CMD was placed at the RVA of an anesthetized pig (Landrace, 45kg) via the internal jugular vein. Arterial and RV pressure were recorded. The energy generated by the device was continuously monitored using a portable data acquisition system during steady state and then during induced tachycardia (isoproterenol), bradycardia (adenosine) and hypotension (pentobarbital). Placement of the device was uncomplicated. The figure illustrates the effect of 4 mcg isoproterenol on HE from device. In steady state (80 bpm, BP 100/60) the energy generated by each cardiac cycle was 4.3μJ (variance ± 0.8μJ). Incremental changes in heart rate produced a corresponding increase in HE e.g. 104 to 128 bpm produced 140% increase in HE (10.0μJ). Relative bradycardia/hypotension following adenosine/pentobarbitol administration produced a proportionate decrease in HE. Post mortem examination demonstrated no significant endocardial trauma. This study has demonstrated the feasibility of energy harvesting of cardiac motion. The device produced 17% of the energy required to power a conventional pacemaker. With further material modification it is envisaged that HE will be efficient enough to allow for complete and indefinite powering of pacemakers.

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