共查询到20条相似文献,搜索用时 46 毫秒
1.
The influence of sound waves on the stationary membrane conductivity of the axon membrane in myelinated nerve was investigated. Sound fields with frequencies within the auditory limit shift the transition voltage Vtr and correspondingly the threshold voltage of the action potential in polarisation direction. The results indicate that these changes of the electrical membrane behavior are due to a direct mechanical interaction between low frequency sound fields and membrane structure. 相似文献
2.
The mechanism by which static and low-frequency magnetic fields are transduced into biological signals responsible for reported effects on brain electrical activity is not yet ascertained. To test the hypothesis that fields can cause a subthreshold change in the resting membrane potential of excitable cells, we measured changes in transmembrane current under voltage clamp produced in SH-SY5Y neuroblastoma cells, using the patch-clamp method in the whole-cell configuration. In separate experiments, cells were exposed to static fields of 1, 5, and 75 G, to time-varying fields of 1 and 5 G, and to combined static and time-varying fields tuned for resonance of Na+, K+, Ca2+, or H+. To increase sensitivity, measurements were made on cells connected by gap junctions. For each cell, the effect of the field was evaluated on the basis of 100 trials consisting of a 5-s exposure immediately followed by a 5-s control period. In each experiment, the field had no discernible effect on the transmembrane current in the vicinity of zero current (- 50 mV voltage clamp). The sensitivity of the measuring system was such that we would have detected a current corresponding to a change in membrane potential as small as 38 microV. Consequently, if sensitivity of mammalian cells to magnetic fields is mediated by subthreshold changes in membrane potential, as in sensory transduction of sound, light, and other stimuli, then the ion channels responsible for the putative changes are probably present only in specialized sensory neurons or neuroepithelial cells. A change in transmembrane potential in response to magnetic fields is not a general property of excitable cells in culture. 相似文献
3.
R. B. Bajnath J. A. Groot H. R. de Jonge M. Kansen J. Bijman 《Cellular and molecular life sciences : CMLS》1993,49(4):313-316
In excised inside-out membrane patches of the human colon carcinoma HT-29cl.19A cells a large conductance (373±10 pS) chloride channel was found. Channel activity could only be observed after excision of patches from cells incubated with calcium ionophore. The channel was never observed in cell-attached patches. The channel was strongly voltage dependent, being open only between +30 and –30 mV clamp potentials. The selectivity sequence among anions, deduced from reversal potentials, was I>Br>Cl>F>gluconate. The PNa/PCl was 0.09. Although a similar type of channel, has been described earlier, this is the first report stating its appearance in patches of intestinal epithelial cells requiring the combined action of Ca2+ ionophore and excision, suggesting its control by an intracellular compound. 相似文献
4.
Jana Fischer Gunnar Kleinau Claudia Rutz Denise Zwanziger Noushafarin Khajavi Anne Müller Maren Rehders Klaudia Brix Catherine L. Worth Dagmar Führer Heiko Krude Burkhard Wiesner Ralf Schülein Heike Biebermann 《Cellular and molecular life sciences : CMLS》2018,75(12):2227-2239
G-protein-coupled receptors (GPCRs) can constitute complexes with non-GPCR integral membrane proteins, while such interaction has not been demonstrated at a single molecule level so far. We here investigated the potential interaction between the thyrotropin receptor (TSHR) and the monocarboxylate transporter 8 (MCT8), a member of the major facilitator superfamily (MFS), using fluorescence cross-correlation spectroscopy (FCCS). Both the proteins are expressed endogenously on the basolateral plasma membrane of the thyrocytes and are involved in stimulation of thyroid hormone production and release. Indeed, we demonstrate strong interaction between both the proteins which causes a suppressed activation of Gq/11 by TSH-stimulated TSHR. Thus, we provide not only evidence for a novel interaction between the TSHR and MCT8, but could also prove this interaction on a single molecule level. Moreover, this interaction forces biased signaling at the TSHR. These results are of general interest for both the GPCR and the MFS research fields. 相似文献
5.
Katarzyna Kwiatkowska 《Cellular and molecular life sciences : CMLS》2010,67(23):3927-3946
Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] is a minor lipid of the inner leaflet of the plasma membrane that controls the activity of numerous proteins and serves
as a source of second messengers. This multifunctionality of PI(4,5)P2 relies on mechanisms ensuring transient appearance of PI(4,5)P2 clusters in the plasma membrane. One such mechanism involves phosphorylation of PI(4)P to PI(4,5)P2 by the type I phosphatidylinositol-4-phosphate 5-kinases (PIP5KI) at discrete membrane locations coupled with PI(4)P delivery/synthesis
at the plasma membrane. Simultaneously, both PI(4)P and PI(4,5)P2 participate in anchoring PIP5KI at the plasma membrane via electrostatic bonds. PIP5KI isoforms are also selectively recruited
and activated at the plasma membrane by Rac1, talin, or AP-2 to generate PI(4,5)P2 in ruffles and lamellipodia, focal contacts, and clathrin-coated pits. In addition, PI(4,5)P2 can accumulate at sphingolipid/cholesterol-based rafts following activation of distinct membrane receptors or be sequestered
in a reversible manner due to electrostatic constrains posed by proteins like MARCKS. 相似文献
6.
The effects of dantrolene on myelinated frog nerve fibers were studied in voltage clamp experiments. Dantrolene shifted the potential-dependent parameters describing Na+ permeability towards more negative membrane potentials. The findings are interpreted as a change in the negative surface charge of the membrane. 相似文献
7.
S. Akselrod J. Richter E. M. Landau Y. Lass 《Cellular and molecular life sciences : CMLS》1977,33(8):1058-1060
Summary Steady membrane voltage fluctuations have been observed in atrial muscle fibres of the carp. These voltage fluctuations produce minute mechanical oscillations, as revealed by an interference contrast microscope. The steady voltage fluctuations may be related to abnormal automaticity in the heart.Supported by the U.S. Israel Binational Science Foundation, Jerusalem, and is part of a thesis to be submitted by Ms Akselrod to the Tel-Aviv University. We thank Ms M. Bendikowski for her efficient technical assistance. 相似文献
8.
G. Deliconstantinos M. Mykoniatis D. Papadimitriou 《Cellular and molecular life sciences : CMLS》1986,42(2):181-183
Summary Modulations in rat hepatic microsomal UDP-glucuronyl transferase activity have been observed during carbon tetrachloride (CCl4) poisoning, with a large decrease in the enzyme cooperativity and increase in the membrane fluidity, occurring 30 min after administration. The results strengthen the possibility that an increase in microsomal membrane fluidity may be an early key event in liver injury induced by CCl4.Acknowledgments. This work was supported by funds of the University of Athens. 相似文献
9.
《Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics》2000,31(2):201-226
In recent articles, Zangari (1994) and Karakostas (1997) observe that while an ε-extended version of the proper orthochronous Lorentz group O↑+ (1,3) exists for values of ε not equal to zero, no similar ε-extended version of its double covering group SL(2, C) exists (where ε=1−2εR, with εR the non-standard simultaneity parameter of Reichenbach). Thus, they maintain, since SL(2, C) is essential in describing the rotational behaviour of half-integer spin fields, and since there is empirical evidence for such behaviour, ε-coordinate transformations for any value of ε≠0 are ruled out empirically. In this article, I make two observations:
(a) | There is an isomorphism between even-indexed 2-spinor fields and Minkowski world-tensors which can be exploited to obtain generally covariant expressions of such spinor fields. |
(b) | There is a 2-1 isomorphism between odd-indexed 2-spinor fields and Minkowski world-tensors which can be exploited to obtain generally covariant expressions for such spinor fields up to a sign. Evidence that the components of such fields do take unique values is not decisive in favour of the realist in the debate over the conventionality of simultaneity in so far as such fields do not play a role in clock synchrony experiments in general, and determinations of the one-way speed of light in particular. |