scholarly journals LOCALIZATION AND PROPERTIES OF THE CHOLINESTERASE IN CRUSTACEAN MUSCLE

1973 ◽  
Vol 59 (2) ◽  
pp. 407-420 ◽  
Author(s):  
Neil I. Spielholz ◽  
William G. Van der Kloot
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Blood Cells ◽  
Substrate Inhibition ◽  
Frozen Sections ◽  
Flexor Muscle ◽  
Muscle Enzyme ◽  
Crustacean Muscle ◽  
Dense Deposits ◽  
Whole Muscle ◽  
Kinetics Of

Cholinesterase (ChE) activity is present in crustacean muscle extracts. However, since acetylcholine (ACh) is not a neuromuscular transmitter in these animals, the role and exact localization of ChE was unknown. The histochemical localization of the enzyme was studied in whole muscle and in the sarcoplasmic reticulum fraction of the extract, 50-µm frozen sections of glutaraldehyde-fixed crayfish tail flexor muscle were incubated with acetylthiocholine (ATC) as substrate, and examined under the electron microscope. After some modifications in published techniques, dense deposits were found associated with the sarcolemma, sarcolemmal invaginations, and transverse tubules. No deposits were found in 10-4 M eserine, or if butyrylthiocholine (BTC) was substituted for ATC. The vesicles in the sarcoplasmic reticulum fraction which demonstrate the activity must represent minced bits of these membranes. Using a spectrophotometric method, the kinetics of the crustacean muscle enzyme was compared to the acetylcholinesterase (AChE) on mammalian red blood cells and in the lobster ventral nerve cord. Surprisingly, and contrary to previous reports, the crustacean muscle enzyme did not demonstrate substrate inhibition. While a number of similarities to AChE were found, this lack of substrate inhibition makes questionable an unequivocal similarity with classical AChE.

Kinetics of calcium uptake by isolated sarcoplasmic reticulum vesicles using flash photolysis of caged ATP

Biochemistry ◽  
1983 ◽  
Vol 22 (23) ◽  
pp. 5254-5261 ◽  
Author(s):  
Dorothy H. Pierce ◽  
Antonio Scarpa ◽  
Michael R. Topp ◽  
J. Kent Blasie
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Uptake ◽  
Flash Photolysis ◽  
Caged Atp ◽  
Kinetics Of

The effects of acetylcholine and atropine on the 22Na+ permeability of intestinal smooth muscle vesicles

1978 ◽  
Vol 56 (6) ◽  
pp. 921-925
Author(s):  
L. Spero
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Membrane Vesicles ◽  
Intestinal Smooth Muscle ◽  
Erythrocyte Ghosts ◽  
Muscarinic Agonists ◽  
Plasma Membrane Vesicles ◽  
Muscle Plasma Membrane ◽  
Whole Muscle ◽  
Kinetics Of

A technique is described which has enabled us to measure changes in 22Na+ efflux from smooth muscle plasma membrane vesicles. The resting 22Na+ efflux from these sealed vesicles showed a concentration-dependent increase in response to acetylcholine and other muscarinic agonists, in similar concentrations to those which increased 42K+ efflux in whole muscle. The kinetics of this efflux were complex and could not be described by less than three exponential processes. The response to agonists has, therefore, been characterized by measurement of the half-life of 22Na+ efflux (t1/2). The acetylcholine effect was inhibited by atropine, but unlike the situation in the whole muscle, this inhibition was noncompetitive. Tubocuraine (a nicotinic antagonist) had no effect on this acetylcholine response. Atropine has no effect by itself on the resting 22Na+ efflux, neither did tetrodotoxin or ouabain. 22Na+ efflux from erythrocyte ghosts and liposomes, prepared from lipid extracts of the smooth muscle plasma membrane, was not modified by acetylcholine or atropine.

scholarly journals Transmembrane mobility of phospholipids in sickle erythrocytes: effect of deoxygenation on diffusion and asymmetry

Blood ◽  
1991 ◽  
Vol 77 (4) ◽  
pp. 849-854 ◽  
Author(s):  
N Blumenfeld ◽  
A Zachowski ◽  
F Galacteros ◽  
Y Beuzard ◽  
PF Devaux
Keyword(s):  
Sickle Cell ◽  
Blood Cells ◽  
Cell Disease ◽  
Aminophospholipid Translocase ◽  
Outer Leaflet ◽  
First Case ◽  
Sickle Erythrocytes ◽  
Dependent Transport ◽  
The Relationship ◽  
Kinetics Of

Abstract We studied the effect of sickling on the transmembrane reorientation and distribution of phospholipids in the red blood cells of patients homozygous for sickle cell anemia (SS). To this purpose, we followed the redistribution kinetics of trace amounts of spin-labeled analogues of natural phospholipids first introduced in the membrane outer leaflet of normal or sickle erythrocytes exposed to air or nitrogen. Deoxygenation had no effect on the lipid redistribution kinetics in normal (AA) cell membranes. At atmospheric pO2, unfractionated SS cells were not different from normal cells. However, on deoxygenation inducing sickling, phosphatidylcholine passive diffusion was accelerated and the rate of the adenosine triphosphate-dependent transport of aminophospholipids was reduced, especially for phosphatidylserine. The stationary distribution of the aminophospholipids between the two leaflets was slightly less asymmetric, a phenomenon more pronounced with phosphatidylethanolamine. These changes were rapidly reversible on reoxygenation. When SS cells were separated by density, both dense and light cells exhibited the properties cited above. However, dense cells exposed to air possessed a lower aminophospholipid transport rate. These data favor the relationship between aminophospholipid translocase activity and phospholipid transmembrane asymmetry. Sickle cell disease is the first case of aminophospholipid translocase pathology.

Kinetics of Na-Li exchange in high and low K sheep red blood cells

1989 ◽  
Vol 257 (1) ◽  
pp. C58-C64 ◽  
Author(s):  
K. H. Ryu ◽  
N. C. Adragna ◽  
P. K. Lauf
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Cell Types ◽  
Sheep Red Blood Cells ◽  
High K ◽  
Ping Pong ◽  
Order Of Magnitude ◽  
Low K ◽  
Kinetics Of ◽  
System Operating

The kinetic parameters and transport mechanism of Na-Li exchange were studied in both low K (LK) and high K (HK) sheep red blood cells with cellular Na [( Na]i) and Li concentrations [( Li]i) adjusted by the nystatin technique (Nature New Biol. 244: 47-49, 1973 and J. Physiol. Lond. 283: 177-196, 1978). Maximum velocities (Vm) for Li fluxes and half-activation constants (K1/2) for Li and Na of the Na-Li exchanger were determined. The K1/2 values for both Li and Na appeared to be similar in both cell types, although they were about two to three times lower on the inside than on the outside of the membrane. Furthermore, the K1/2 values for Li were at least an order of magnitude smaller than those for Na, suggesting substantial affinity differences for these two cations. The Vm values for Li fluxes, on the other hand, appear to be lower in HK than in LK cells. When Na and Li fluxes were measured simultaneously, a trans stimulatory effect by Na on Li fluxes was observed. From measurements of Li influx at different concentrations of external Li and different [Na]i, the ratio of the apparent Vm to the apparent external Li affinity was calculated to be independent of [Na]i for both types of sheep red blood cells. Similar trans effects of external Na were observed on Li efflux at varying [Li]i. These results are expected for a system operating by a “ping-pong” mechanism.

Ontogeny of carnitine biosynthesis in Sus scrofa domesticus, inferred from γ-butyrobetaine hydroxylase (dioxygenase) activity and substrate inhibition

2020 ◽  
Vol 319 (1) ◽  
pp. R43-R49
Author(s):  
Xi Lin ◽  
Pasha A. Lyvers Peffer ◽  
Jason Woodworth ◽  
Jack Odle
Keyword(s):  
Sus Scrofa ◽  
Specific Activity ◽  
Substrate Inhibition ◽  
Biosynthesis Pathway ◽  
Fresh Tissue ◽  
Tissue Homogenates ◽  
Liver And Kidney ◽  
Sus Scrofa Domesticus ◽  
Kinetics Of ◽  
Dioxygenase Activity

γ-Butyrobetaine hydroxylase (γ-BBH) is the last limiting enzyme of the l-carnitine biosynthesis pathway and plays an important role in catalyzing the hydroxylation of γ-butyrobetaine (γ-BB) to l-carnitine. To study the developmental effect of substrate concentration on the enzyme’s specific activity, kinetics of γ-BBH were measured in liver and kidney from newborn and 1-, 7-, 21-, 35-, 56-, and 210-day-old domestic pigs. Fresh tissue homogenates were assayed under nine concentrations of γ-BB from 0 to 1.5 mM. Substrate inhibition associated with age was observed at ≥0.6 mM of γ-BB. Hepatic activity was low at birth but increased after 1 day. By 21 days, the activity rose by 6.6-fold ( P < 0.05) and remained constant after 56 days. Renal activity was higher than in liver at birth but remained constant through 35 days. By 56 days, the velocity increased by 44% over the activity at birth ( P < 0.05). The apparent Km for γ-BB at birth on average was 2.8-fold higher than at 1 day. The Km value was 60% higher in kidney than liver during development but showed no difference in adult pigs. The total organ enzyme activity increased by 130-fold for liver and 18-fold for kidney as organ weight increased from birth to 56 days. In conclusion, age and substrate affect γ-BBH specific activity and Km for γ-BB in liver and kidney. Whereas the predominant organ for carnitine synthesis is likely the kidney at birth, the liver appears to predominate after the pig exceeds 7 days of age.

Differentiation of Na(+)-K+ pumps of low-K+ sheep red blood cells is promoted by Lp membrane antigens

1993 ◽  
Vol 265 (1) ◽  
pp. C99-C105 ◽  
Author(s):  
Z. C. Xu ◽  
P. B. Dunham ◽  
B. Dyer ◽  
R. Blostein
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Rat Kidney ◽  
Striking Increase ◽  
Sheep Red Blood Cells ◽  
High K ◽  
Membrane Antigens ◽  
Low K ◽  
Kinetics Of

Na(+)-K+ pumps of red blood cells from sheep of the low-K+ (LK) phenotype undergo differentiation during circulation, manifested in part by a striking increase in sensitivity to inhibition by intracellular K+ (Ki). Pumps of red blood cells from sheep from the allelic phenotype, high K+ (HK), do not undergo this type of maturation. The hypothesis was tested that the Lp antigen, found on LK but not HK cells, is responsible for the maturation of LK pumps. Lp antigens have been shown to inhibit LK pumps because anti-Lp antibody stimulates the pumps by relieving inhibition by the antigen. Lp antigens were recently shown to be molecular entities separate from Na(+)-K+ pumps [Xu, Z.-C., P. Dunham, J. Munzer, J. Silvius, and R. Blostein. Am. J. Physiol. 263 (Cell Physiol. 32): C1007-C1014, 1992]. The test of the hypothesis was to modify the Lp antigens of immature LK red blood cells with two kinds of treatments, anti-Lp antibody and trypsinization (which cleaves Lp), and to observe the effects of these treatments on maturation of pumps during culture of the cells in vitro. Both of these treatments prevented the maturation of the kinetics of the pumps to the Ki-sensitive pattern, supporting the hypothesis that interaction of the pumps with Lp antigens is responsible for the maturation of the pumps. Strong supportive evidence came from experiments on Na(+)-K+ pumps from rat kidney delivered into immature LK sheep red blood cells by microsome fusion.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Comparison of the kinetics of calcium transport in vesicular dispersions and oriented multilayers of isolated sarcoplasmic reticulum membranes

1983 ◽  
Vol 44 (3) ◽  
pp. 365-373 ◽  
Author(s):  
D.H. Pierce ◽  
A. Scarpa ◽  
D.R. Trentham ◽  
M.R. Topp ◽  
J.K. Blasie
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Transport ◽  
Kinetics Of
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