Ultrastructure of Smooth Muscle

Somlyo, Andrew P.; Somlyo, Avril V.

doi:10.1007/978-1-4684-2751-6_1

Cited by 78 publications

(102 citation statements)

References 120 publications

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“…After destruction of the SR with Triton X-100, only the relaxant effect of caffeine remained. The relaxation of the caffeine contracture represents a secondary, inhibitory effect independent of Ca release and is also observed in intact smooth muscle (8,24 (2,(30)(31)(32). We emphasize that, in this as in previous studies of smooth muscle made permeable with saponin (31,32), the ATP-dependent Ca pump could not be located in the (hyperpermeable) plasma membrane.…”

supporting

confidence: 56%

“…The release of intracellular Ca does not require influx of extracellular Ca (5-7) and can be triggered by pharmacomechanical coupling, a process independent of changes in surface membrane potential (8). Recent electron probe analytic studies have directly demonstrated that the sarcoplasmic reticulum (SR) is the source of intracellular Ca released by norepinephrine in rabbit main pulmonary artery (MPA) (1), portal vein (7), and, probably, other smooth muscles.…”

mentioning

confidence: 99%

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Inositol trisphosphate-induced calcium release and contraction in vascular smooth muscle.

Somlyo¹,

Bond²,

Somlyo³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

359

142

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Inositol 1,4,5-trisphosphate (InsP3) caused Ca release and tension development in rabbit main pulmonary artery smooth muscle permeabilized with saponin or digitonin. Both of these responses to single additions of uM) were repeatable and occurred in the presence of 0.0-1.9 mM free Mg +. Sustained contractions were induced by InsP3. The amount of Ca released by InsP3, measured with a Ca21-selective electrode, was also estimated to be sufficient to stimulate contraction in intact smooth muscle. Ca release was not influenced by inhibitors of mitochondrial oxidative phosphorylation. The uptake of Ca21 from the medium into the InsP3-sensitive pool was ATP-dependent. The present results support the hypothesis that, in smooth muscle, InsP3 is the messenger, or one of the messengers, involved in transmitterinduced (pharmacomechanical) Ca release from the sarcoplasmic reticulum, which is the intracellular Ca store identified previously as the source of Ca released by norepinephrine in main pulmonary artery.Activation of smooth muscle by transmitters and drugs involves, at least in part, the release of intracellular Ca (1-3), followed by Ca activation ofthe calmodulin-regulated myosin light chain kinase (4). The release of intracellular Ca does not require influx of extracellular Ca (5-7) and can be triggered by pharmacomechanical coupling, a process independent of changes in surface membrane potential (8). Recent electron probe analytic studies have directly demonstrated that the sarcoplasmic reticulum (SR) is the source of intracellular Ca released by norepinephrine in rabbit main pulmonary artery (MPA) (1), portal vein (7), and, probably, other smooth muscles. However, until very recently, the mechanism through which drugs and transmitters released Ca from the SR remained unknown.The recognition, in nonmuscle cells, that stimulation of phosphatidylinositol turnover, stimulated by cholinergic agents and other secretogogues (9, 10), is associated with the production of a metabolite, inositol 1,4,5-trisphosphate (Ins-P3), that can release Ca from the endoplasmic reticulum (11, 12) indicated that InsP3 may also function as an excitatory messenger in smooth muscle. In this study, we demonstrate that InsP3 can, indeed, release Ca from smooth muscle cells of the rabbit MPA, as indicated by Ca2+-selective electrode measurements and by InsP3-induced contraction of vascular strips permeabilized with saponin or digitonin. The quantity of Ca2' released by InsP3, like that released from the SR by norepinephrine in this tissue (1), is sufficient for the activation of contraction. These and other recent studies of phosphatidylinositol turnover (including its stimulation by norepinephrine) and of the effects of InsP3 in smooth muscle (13)(14)(15)(16)(17) provide further evidence for the possibility that InsP3 is a physiological messenger mediating agonist-induced Ca release in smooth muscle. MATERIALS AND METHODSTissue Preparation. Male New Zealand rabbits (1-2 kg of body weight) were killed by a blow on the back of the head...

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supporting

confidence: 56%

mentioning

confidence: 99%

Inositol trisphosphate-induced calcium release and contraction in vascular smooth muscle.

Somlyo¹,

Bond²,

Somlyo³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

359

142

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“…Each cell profile was divided into a series of grids 5 cm x 5 cm. The number of actin (5-8 nm), myosin (15-18 nm), and intermediate (10 nm) filaments (50)(51)(52) were counted per grid area, excluding areas containing mitochondria and nuclei, and then expressed per micrometer. Each cell profile was divided into peripheral and central portions .…”

Section: Methodsmentioning

confidence: 99%

Hypertrophy-induced increase of intermediate filaments in vascular smooth muscle.

Berner¹,

Somlyo²,

Somlyo³

1981

The Journal of Cell Biology

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The distribution of filaments was studied in hypertrophied rabbit vascular smooth muscle . Hypertrophy was induced by partial ligation of the portal-anterior mesenteric vein . 14 d after ligation, there was an approximately threefold increase in the number of intermediate filaments per cross-sectional area, as compared to control values . The actin :intermediate:myosin filament ratio was 15 :1 .1 :1 in control and 15 :3 .5 :0 .5 in hypertrophied portal-anterior mesentric vein vascular smooth muscle . Comparison of the filament ratios with the increase in volume density of the hypertrophied cells suggests that the number of myosin filaments per cell profile remained approximately the same as in controls, whereas the number of actin filaments increased in proportion to the increase in cell volume .Intermediate (10 nm diameter) filaments are ubiquitous components ofmost, if not all, eukaryotic cells (see reference 39 for review) . In nonneural tissue, they were first described by Ishikawa et al. (35) in cultured cells and distinguished from actin filaments through the difference in size and the failure of the 10-nm filaments to bind the heavy meromyosin subfragment of myosin. Recent studies have shown that the major component ofthe intermediate filaments in muscle is a protein of 50,000-55,000 mol wt (15). In nonmuscle cells, other than nerve, a related protein of slightly higher mass (55,000-58,000 daltons) forms the 10-nm filaments, although the two proteins may also coexist in the same cell (5,20,24). A marked increase in the number of intermediate filaments, frequently in the form ofcables, can be induced in muscle and in other cells by drugs such as cytochalasin B and Colcemid (CIBA Pharmaceutical Co., Summit, N. J.) (4,29,33,34,38,55,56) .In normal adult mammalian smooth muscle, intermediate filaments generally surround dense bodies on which actin filaments insert (2) . Intermediate filaments are very numerous in cultured vascular (45-47) and other smooth muscles (11)(12)(13)60). In previous studies of normal adult vascular smooth muscle, occasional cells were found containing massive quantities ofintermediate filaments that appeared to displace the normal actin and myosin filament lattice (50, 52) . Although it was recognized that such proliferation of intermediate filaments in adult smooth muscle represented some form of cellular pathology, its specific cause was not known . We now show that a large increase in the number of intermediate filaments in vascular smooth muscle occurs during hypertrophy induced by increasing vascular distending pressure. In addition, we also 96 describe changes found in the number and distribution ofactin and myosin filaments of hypertrophied vascular smooth muscle . These studies are being pursued to enable us to eventually distinguish the secondary effects of increased pressure on vascular smooth muscle from possible primary pathology of cell organelles that may cause hypertension. MATERIALS AND METHODSNew Zealand white male rabbits (1 .8-2 .7 kg) were anesthetized w...

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“…The failure to achieve specific labeling of c -adrenergic receptors with 3-halogenoethyl amines (16)(17)(18)(19)(20)(21)(22)(25)(26)(27) was attributed to the fact that the irreversible blockade were not the result of alkylation of the a-adrenergic sites but rather the result of inhibition of `Ca sites' or `Ca binding/mobilizing sites' (38)(39)(40). Recently Ohmura et al (41,42) showed that the irreversible blockade of contraction to acet} lcholine, K+ or Ba-+ was due to inhibition of `Ca sites' by dibenamine.…”

Section: Discussionmentioning

confidence: 99%

Purification of Histamine Receptor (Vi) an Improved Double Labeling Method With “Double Protection”

Uchida

1977

Japanese Journal of Pharmacology

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Ultrastructure of Smooth Muscle

Cited by 78 publications

References 120 publications

Inositol trisphosphate-induced calcium release and contraction in vascular smooth muscle.

Inositol trisphosphate-induced calcium release and contraction in vascular smooth muscle.

Hypertrophy-induced increase of intermediate filaments in vascular smooth muscle.

Purification of Histamine Receptor (Vi) an Improved Double Labeling Method With “Double Protection”

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