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.

Preferential support of Ca 2+ uptake in smooth muscle plasma membrane vesicles by an endogenous glycolytic cascade

1989 ◽  
Vol 3 (11) ◽  
pp. 2298-2301 ◽  
Author(s):  
Richard J. Paul ◽  
Christopher D. Hardin ◽  
Luc Raeymaekers ◽  
Frank Wuytack ◽  
Rik Casteels
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Membrane Vesicles ◽  
Plasma Membrane Vesicles ◽  
Muscle Plasma Membrane

scholarly journals Comparison of endogenous and exogenous sources of ATP in fueling Ca2+ uptake in smooth muscle plasma membrane vesicles.

1992 ◽  
Vol 99 (1) ◽  
pp. 21-40 ◽  
Author(s):  
C D Hardin ◽  
L Raeymaekers ◽  
R J Paul
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Calcium Uptake ◽  
Membrane Vesicles ◽  
Glycolytic Enzyme ◽  
Calcium Pump ◽  
Bulk Solution ◽  
Plasma Membrane Vesicles ◽  
Atp Production ◽  
Muscle Plasma Membrane

A smooth muscle plasma membrane vesicular fraction (PMV) purified for the (Ca2+/Mg2+)-ATPase has endogenous glycolytic enzyme activity. In the presence of glycolytic substrate (fructose 1,6-diphosphate) and cofactors, PMV produced ATP and lactate and supported calcium uptake. The endogenous glycolytic cascade supports calcium uptake independent of bath [ATP]. A 10-fold dilution of PMV, with the resultant 10-fold dilution of glycolytically produced bath [ATP] did not change glycolytically fueled calcium uptake (nanomoles per milligram protein). Furthermore, the calcium uptake fueled by the endogenous glycolytic cascade persisted in the presence of a hexokinase-based ATP trap which eliminated calcium uptake fueled by exogenously added ATP. Thus, it appears that the endogenous glycolytic cascade fuels calcium uptake in PMV via a membrane-associated pool of ATP and not via an exchange of ATP with the bulk solution. To determine whether ATP produced endogenously was utilized preferentially by the calcium pump, the ATP production rates of the endogenous creatine kinase and pyruvate kinase were matched to that of glycolysis and the calcium uptake fueled by the endogenous sources was compared with that fueled by exogenous ATP added at the same rate. The rate of calcium uptake fueled by endogenous sources of ATP was approximately twice that supported by exogenously added ATP, indicating that the calcium pump preferentially utilizes ATP produced by membrane-bound enzymes.

scholarly journals Characterization of L-carnitine transport into rat skeletal muscle plasma membrane vesicles

2000 ◽  
Vol 267 (7) ◽  
pp. 1985-1994 ◽  
Author(s):  
Simona Berardi ◽  
Bruno Stieger ◽  
Bruno Hagenbuch ◽  
Ernesto Carafoli ◽  
Stephan Krähenbühl
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Membrane Vesicles ◽  
Rat Skeletal Muscle ◽  
Plasma Membrane Vesicles ◽  
Muscle Plasma Membrane ◽  
Carnitine Transport

Effect of disulphonic stilbenes on Ca2+ transport in smooth muscle plasma membranes

1984 ◽  
Vol 62 (9) ◽  
pp. 1233-1238 ◽  
Author(s):  
P. K. Rangachari ◽  
A. K. Grover ◽  
E. E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Plasma Membranes ◽  
Circular Muscle ◽  
Membrane Vesicles ◽  
Plasma Membrane Vesicles ◽  
Disulphonic Acid

We studied the effects of two disulphonic stilbenes, 4′,4′-diisothiocyano-2,2′-stilbene disulphonic acid (DIDS) and 4-acetamido-4′-isothiocyano-2,2′-stilbene disulphonic acid (SITS), on Ca2+ transport by plasma membrane vesicles from the circular muscle of the dog stomach. Both compounds inhibited ATP-dependent Ca2+ uptake and reduce the leak from loaded vesicles. The inhibition produced could not be significantly reduced by either permeant anions or by increasing the level of free Ca2+. The effects of DIDS could be rendered irreversible by incubating the membranes with this agent at 37 °C.

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