scholarly journals Characterization of K + currents using an in situ patch clamp technique in body wall muscle cells from Caenorhabditis elegans

2002 ◽  
Vol 544 (2) ◽  
pp. 373-384 ◽  
Author(s):  
Maëlle Jospin ◽  
Marie‐Christine Mariol ◽  
Laurent Ségalat ◽  
Bruno Allard
Keyword(s):  
Caenorhabditis Elegans ◽  
Patch Clamp ◽  
Body Wall ◽  
Muscle Cells ◽  
Body Wall Muscle ◽  
Patch Clamp Technique ◽  
Clamp Technique ◽  
K Currents

scholarly journals The L-type voltage-dependent Ca2+ channel EGL-19 controls body wall muscle function in Caenorhabditis elegans

2002 ◽  
Vol 159 (2) ◽  
pp. 337-348 ◽  
Author(s):  
Maëlle Jospin ◽  
Vincent Jacquemond ◽  
Marie-Christine Mariol ◽  
Laurent Ségalat ◽  
Bruno Allard
Keyword(s):  
Caenorhabditis Elegans ◽  
Body Wall ◽  
Muscle Cells ◽  
Membrane Depolarization ◽  
Cellular Level ◽  
Body Wall Muscle ◽  
K Channel ◽  
Channel Blockers ◽  
Patch Clamp Technique ◽  
Voltage Dependent

Caenorhabditis elegans is a powerful model system widely used to investigate the relationships between genes and complex behaviors like locomotion. However, physiological studies at the cellular level have been restricted by the difficulty to dissect this microscopic animal. Thus, little is known about the properties of body wall muscle cells used for locomotion. Using in situ patch clamp technique, we show that body wall muscle cells generate spontaneous spike potentials and develop graded action potentials in response to injection of positive current of increasing amplitude. In the presence of K+ channel blockers, membrane depolarization elicited Ca2+ currents inhibited by nifedipine and exhibiting Ca2+-dependent inactivation. Our results give evidence that the Ca2+ channel involved belongs to the L-type class and corresponds to EGL-19, a putative Ca2+ channel originally thought to be a member of this class on the basis of genomic data. Using Ca2+ fluorescence imaging on patch-clamped muscle cells, we demonstrate that the Ca2+ transients elicited by membrane depolarization are under the control of Ca2+ entry through L-type Ca2+ channels. In reduction of function egl-19 mutant muscle cells, Ca2+ currents displayed slower activation kinetics and provided a significantly smaller Ca2+ entry, whereas the threshold for Ca2+ transients was shifted toward positive membrane potentials.

Ketamine blocks Ca2+-activated K+ channels in rabbit cerebral arterial smooth muscle cells

2003 ◽  
Vol 285 (3) ◽  
pp. H1347-H1355 ◽  
Author(s):  
Jin Han ◽  
Nari Kim ◽  
Hyun Joo ◽  
Euiyong Kim
Keyword(s):  
Smooth Muscle ◽  
Patch Clamp ◽  
Smooth Muscle Cells ◽  
Cerebral Arteries ◽  
Muscle Cells ◽  
Channel Activity ◽  
Patch Clamp Technique ◽  
Arterial Smooth Muscle ◽  
Clamp Technique ◽  
Arterial Smooth Muscle Cells

Although ketamine and Ca2+-activated K+ (KCa) channels have been implicated in the contractile activity regulation of cerebral arteries, no studies have addressed the specific interactions between ketamine and the KCa channels in cerebral arteries. The purpose of this study was to examine the direct effects of ketamine on KCa channel activities using the patch-clamp technique in single-cell preparations of rabbit middle cerebral arterial smooth muscle. We tested the hypothesis that ketamine modulates the KCa channel activity of the cerebral arterial smooth muscle cells of the rabbit. Vascular myocytes were isolated from rabbit middle cerebral arteries using enzymatic dissociation. Single KCa channel activities of smooth muscle cells from rabbit cerebral arteries were recorded using the patch-clamp technique. In the inside-out patches, ketamine in the micromolar range inhibited channel activity with a half-maximal inhibition of the ketamine conentration value of 83.8 ± 12.9 μM. The Hill coefficient was 1.2 ± 0.3. The slope conductance of the current-voltage relationship was 320.1 ± 2.0 pS between 0 and +60 mV in the presence of ketamine and symmetrical 145 mM K+. Ketamine had little effect on either the voltage-dependency or open- and closed-time histograms of KCa channel. The present study clearly demonstrates that ketamine inhibits KCa channel activities in rabbit middle cerebral arterial smooth muscle cells. This inhibition of KCa channels may represent a mechanism for ketamine-induced cerebral vasoconstriction.

scholarly journals Type IV Collagen Is Detectable in Most, but Not All, Basement Membranes of Caenorhabditis elegans and Assembles on Tissues That Do Not Express It

1997 ◽  
Vol 137 (5) ◽  
pp. 1171-1183 ◽  
Author(s):  
Patricia L. Graham ◽  
Jeffrey J. Johnson ◽  
Shaoru Wang ◽  
Marion H. Sibley ◽  
Malini C. Gupta ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Body Wall ◽  
Type Iv Collagen ◽  
Fluorescent Protein ◽  
Muscle Cells ◽  
Basement Membranes ◽  
Body Wall Muscle ◽  
Collagen Molecule ◽  
C Elegans ◽  
Type Iv

Type IV collagen in Caenorhabditis elegans is produced by two essential genes, emb-9 and let-2, which encode α1- and α2-like chains, respectively. The distribution of EMB-9 and LET-2 chains has been characterized using chain-specific antisera. The chains colocalize, suggesting that they may function in a single heterotrimeric collagen molecule. Type IV collagen is detected in all basement membranes except those on the pseudocoelomic face of body wall muscle and on the regions of the hypodermis between body wall muscle quadrants, indicating that there are major structural differences between some basement membranes in C. elegans. Using lacZ/green fluorescent protein (GFP) reporter constructs, both type IV collagen genes were shown to be expressed in the same cells, primarily body wall muscles, and some somatic cells of the gonad. Although the pharynx and intestine are covered with basement membranes that contain type IV collagen, these tissues do not express either type IV collagen gene. Using an epitope-tagged emb-9 construct, we show that type IV collagen made in body wall muscle cells can assemble into the pharyngeal, intestinal, and gonadal basement membranes. Additionally, we show that expression of functional type IV collagen only in body wall muscle cells is sufficient for C. elegans to complete development and be partially fertile. Since type IV collagen secreted from muscle cells only assembles into some of the basement membranes that it has access to, there must be a mechanism regulating its assembly. We propose that interaction with a cell surface–associated molecule(s) is required to facilitate type IV collagen assembly.

scholarly journals Magnesium induced vascular relaxation and role of Calcium-dependent K+ Channels

2013 ◽  
Vol 1 (1) ◽  
pp. 9-13
Author(s):  
K Upadhyay-Dhungel ◽  
CJ Kim ◽  
A Dhungel
Keyword(s):  
Smooth Muscle ◽  
Patch Clamp ◽  
Smooth Muscle Cells ◽  
Channel Blocker ◽  
Muscle Cells ◽  
K Channel ◽  
Vascular Relaxation ◽  
Patch Clamp Technique ◽  
Calcium Dependent ◽  
K Currents

Background and objectives: Magnesium is established as a neuro-protective agent and now also known as a vasodilator. It has been known for treating vasospasm following subarachnoid hemorrhage. However, its action mechanism in cerebral vascular relaxation is not clear. Potassium channels play a pivotal role in the relaxation of smooth muscle cells. To investigate their role in magnesium-induced relaxation of basilar smooth muscle cells, we examined the effect of magnesium on potassium channels using the patch clamp technique on cells from rabbit basilar artery. Material and Methods: Fresh smooth muscle cells were isolated from the basilar artery by enzyme treatment. Whole cell current recording was done using patch-clamp technique. Appropriate bath solution was used to have potassium current. The effect of Magnesium was observed and to identify the potassium (K+) channel involved in the magnesium-induced currents, different potassium channel blockers were used. Results: Magnesium increased the step pulse-induced outward K+ currents by more than fortyfive percent over control level (p<0.01). The outward K+ current was decreased significantly by application of tetraethylammonium, a non-specific K+ channel blocker, and by iberiotoxin, a largeconductance Ca2+-activated K+ (BKCa) channel blocker, but was not inhibited by glibenclamide an ATP-sensitive K+ (KATP) channel blocker. Magnesium failed to increase the outward K+ currents in the presence of IBX. Conclusion: These results demonstrate that calcium dependent pottassium (BKCa) channels has role in magnesium induced vascular relaxation in rabbit basilar smooth muscle cells and needs to be worked out for human. DOI: http://dx.doi.org/10.3126/jmcjms.v1i1.7880 Janaki Medical College Journal of Medical Sciences (2013) Vol. 1 (1):9-13

scholarly journals Mutations in the sup-38 gene of Caenorhabditis elegans suppress muscle-attachment defects in unc-52 mutants.

Genetics ◽  
1992 ◽  
Vol 132 (2) ◽  
pp. 431-442 ◽  
Author(s):  
E J Gilchrist ◽  
D G Moerman
Keyword(s):  
Caenorhabditis Elegans ◽  
Body Wall ◽  
Muscle Cells ◽  
The Body ◽  
Body Wall Muscle ◽  
Variable Degree ◽  
Loss Of Function ◽  
Uterine Muscle ◽  
Somatic Gonad ◽  
Class 1

Abstract Mutations in the unc-52 locus of Caenorhabditis elegans have been classified into three different groups based on their complex pattern of complementation. These mutations result in progressive paralysis (class 1 mutations) or in lethality (class 2 and 3 mutations). The paralysis exhibited by animals carrying class 1 mutations is caused by disruption of the myofilaments at their points of attachment to the cell membrane in the body wall muscle cells. We have determined that mutations of this class also have an effect on the somatic gonad, and this may be due to a similar disruption in the myoepithelial sheath cells of the uterus, or in the uterine muscle cells. Mutations that suppress the body wall muscle defects of the class 1 unc-52 mutations have been isolated, and they define a new locus, sup-38. Only the muscle disorganization of the Unc-52 mutants is suppressed; the gonad abnormalities are not, and the suppressors do not rescue the lethal phenotype of the class 2 and class 3 mutations. The suppressor mutations on their own exhibit a variable degree of gonad and muscle disorganization. Putative null sup-38 mutations cause maternal-effect lethality which is rescued by a wild-type copy of the locus in the zygote. These loss-of-function mutations have no effect on the body wall muscle structure.

HSP43, a small heat-shock protein localized to specific cells of the vulva and spermatheca in the nematode Caenorhabditis elegans

2000 ◽  
Vol 349 (2) ◽  
pp. 409-412 ◽  
Author(s):  
Lily DING ◽  
E. M. Peter CANDIDO
Keyword(s):  
Caenorhabditis Elegans ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Body Wall ◽  
Small Heat Shock Protein ◽  
Muscle Cells ◽  
Body Wall Muscle ◽  
Nematode Caenorhabditis Elegans ◽  
Punctate Pattern

Heat-shock protein 43 (HSP43) of Caenorhabditis elegans is prominently expressed in the utse cell, which attaches the uterus to the hypodermis, the uv1 cells joining the vulva and the uterus, the spermathecal valve and junctions between cells of the spermathecal cage. In body-wall muscle, HSP43 forms a punctate pattern of circumferential lines, probably corresponding to regions where the hypodermis contacts the muscle cells.

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