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ALTERATIONS IN THE CYTOLOGIC DETAIL OF INTESTINAL SMOOTH MUSCLE CELLS IN VARIOUS STAGES OF CONTRACTION 总被引:24,自引:13,他引:11 下载免费PDF全文
Bernard P. Lane 《The Journal of cell biology》1965,27(1):199-213
The fine structure of the longitudinal layer of the tunica muscularis of the mouse jejunum was studied in various stages of mechanically stimulated contraction. The relaxed cell is long and narrow with smooth cytoplasmic and nuclear contours. As contraction progresses, the cell becomes ellipsoid and its borders exhibit invaginations at the points of myofilamentous attachment to the plasma membrane and vesicle-containing projections of the intervening membrane. These changes are interpreted as representing the deforming forces applied by the myofilaments to the plasma membrane. The nucleus of the contracted cell is shortened and widened, with convolution of its limiting membranes. This alteration, as well as progressive changes in the alignment of cytoplasmic organelles, is thought to be due to forces exerted on the internal structure of the cell by the contractile elements. The myofilaments form a network of oriented bundles during contraction. Aggregates of filaments of two different diameters are noted. The two sizes of filaments intermingle only in small areas of increased density. These dense areas increase in length and number during contraction. A model of the functional organization of the cell is proposed. 相似文献
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Jeffery R. Cook Barbara E. Crute Laura M. Patrone Joseph Gabriels Maureen E. Lane Robert G. van Buskirk 《In vitro cellular & developmental biology. Plant》1989,25(10):914-922
Summary We have analyzed the ability of the physical substratum to modulate both the ultrastructural and protein synthetic characteristics
of the Madin-Darby canine kidney (MDCK) renal cell line. When MDCK cells were seeded on Millipore Millicell CM microporous
membrane cell culture inserts they demonstrated a more columnar organization with an increase in cell density sixfold greater
than the same cells seeded on conventional plastic substrata. After 1 wk postseeding on the microporous membrane a partial
basal lamina was noted, with a contiguous basement membrane being apparent after 2 wk. One-dimensional sodium dodecyl sulfate
gel electrophoresis was used to analyze detergent-solubilized proteins from MDCK cells maintained on plastic substrata vs.
microporous membranes. When proteins were pulse-labeled with [35S]methionine, a 55 kDa protein was evident in the cytosolic extract of cells grown on collagen, laminin, and nontreated plastic
substrata; but this labeled protein was not evident in similar extracts from cells grown on collagen and laminin-coated microporous
membranes. To test if the polarized, basement-membrane secreting phenotype of the MDCK cells could be generated on a microporous
membrane without pretreatment with any extracellular matrix (ECM) components, cells were seeded on the Millipore Millicell
HA (cellulosic) microporous membrane. This type of substrata does not need a coating of ECM components for cell attachment.
A partial basement membrane was formed below cells where the basal surface of the cell was planar, but not in areas where
the cell formed large cytoplasmic extensions into the filter. This led us to the conclusion that the microporous nature of
the substrata can dictate both ultrastructural and protein synthetic activities of MDCK cells. Furthermore, we suggest that
both the planar nature of the basal surface and the microporosity of the substrate are corequisites for the deposition of
the basement membrane. 相似文献
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Adrian S. Dobs Christiane Broussolle M. Daniel Lane 《In vitro cellular & developmental biology. Plant》1989,25(2):112-114
Summary The insulin-producing cell line RINm5F, has been used in short-term experiments to evaluate insulin secretion. We sought to
maintain the responsiveness of these cells to stimuli for up to 2 days. We examined the course of new insulin synthesis over
this period by measuring at intervals immunoreactive insulin (IRI) in two parts: IRI in the medium (M) and IRI extracted from
the cells (C). Control cells were incubated in RPMI 1640/2.8 mM glucose/10% fetal bovine serum/200 μg/ml bacitracin (to prevent
insulin degradation). The addition of dibutyryl cAMP 10 mM to the experimental dishes significantly increased total (M+C)
IRI at 48 hr to 37% above the insulin content of the control dishes (p<0.01). Theophylline 10 mM increased total (M+C) IRI
by 24% over control (p<0.05) after 24 hrs. Glucose, glyceraldehyde, leucine, arginine, glucagon and tolbutamide, other stimulants
of insulin production, had no effect. Under the experimental conditions reported here, including the use of bacitracin, IRI
synthesis can be studied for up to 48 hr.
Portions of this study have been published in abstract form for the 47th Annual Meeting of the American Diabetes Association,
Indianapolis, Indiana, 1987.
Supported in part by the American Diabetic Association, Maryland Affiliate. 相似文献
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Persistent abnormalities in lipoprotein composition and cholesteryl ester transfer following lovastatin treatment 总被引:3,自引:0,他引:3
J D Bagdade J T Lane N Stone M C Ritter P V Subbaiah 《Journal of lipid research》1990,31(7):1263-1269
Optimally effective lipid-lowering agents should not only restore plasma lipids to normal levels but also correct potentially atherogenic alterations in lipoprotein composition and function often present in hyperlipidemic patients. Lovastatin, a competitive inhibitor of cholesterol biosynthesis, clearly lowers plasma cholesterol levels. Its effects on lipoprotein composition and cholesteryl ester transfer (CET), a key step in reverse cholesterol transport, however, are not known. Since abnormalities in CET and lipoprotein composition are present in patients with hypercholesterolemia, we studied these parameters of plasma lipoprotein transport in twelve hypercholesterolemic (HC; Type IIa) subjects (six male, six female) before and 2 months after lovastatin treatment (20 mg qd). Before lovastatin, the free cholesterol (FC)/lecithin (L) ratio in plasma, a new index of cardiovascular risk that reflects lipoprotein surface composition, was abnormally increased (1.18 +/- 0.26 vs controls 0.83 +/- 0.14; P less than 0.001) in very low density lipoproteins (VLDL) and high density lipoprotein-3 (HDL3), and remained so after treatment despite significant declines in whole plasma cholesterol (311.7 +/- 68.2 vs 215.6 +/- 27.2 mg/dl; P less than 0.001), low density lipoprotein (LDL)-cholesterol (206.3 +/- 47.9 vs 146.8 +/- 29.4; P less than 0.001), and apolipoprotein B (149 +/- 30 vs 110 +/- 17; P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献