Membrane patches

The patch-clamp technique is based on the formation of a high resistance seal (109-10lon) between the tip of a glass micropipette and the cell membrane it touches (gigaohm-seal). This technique allows recordings of ionic currents through single ion channels in the intact cell membrane and in isolated membrane patches at a... 

In respiratory epithelial (RE) cells the Cl -conductance was attributed to the ICOR channel. In fact, it was reported by Frizzell et al. and Welsh s laboratories that catecholamines increased the incidence of ICOR channels in cell attached patches of normal RE cells but failed to do so in CF cells [110,111], Later both laboratories presented data on excised membrane patches of RE cells in which the protein kinase A which was added to the cytosolic side produced ICOR channel activity in the normal cells but not in the CF tissues [19,20]. This finding was reproduced by Guggino and coworkers [22] for RE cells and by others for lymphocytes [46]. Protein kinase C at physiological Ca -activities had a comparable effect in normal cells but also failed to function in CF cells [22,112]. 

In our patch clamp studies in excised membrane patches in which we attempted to characterize the Cl we have noted that Cl did not only inhibit the probability of the ICOR channel being open but we also found that the input conductance of the patch was reduced at the same time and with the same time course [72]. We have followed up on this observation and we were able to show that this reduction in input conductance is caused by an inhibition of small ( lOpS) Cl -channels. Hence, we postulate that the same patches containing ICOR channels also contain small (unresolved, cf. section 2.4) Cl -channels which are inhibited reversibly by CL It cannot be excluded at this stage that these small Cl -channels are responsible for the defect in CF. 

A BLM can even be prepared from phospholipid monolayers at the water-air interface (Fig. 6.10B) and often does not then contain unfavourable organic solvent impurities. An asymmetric BLM can even be prepared containing different phospholipids on the two sides of the membrane. A method used for preparation of tiny segments of biological membranes (patch-clamp) is also applied to BLM preparation (Fig. 6.10C). 

OP Hamill, A Marty, E Neher, B Sakman, FJ Sigworth. (1981). Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pfluegers Arch 391 85-100. 

The electrophysiological technique used to measure changes in membrane capacitance is the patch clamp [5,6] in the whole-cell recording mode, where the plasma membrane patch in the pipet is ruptured. In another configuration of the patch clamp, the plasma membrane patch is maintained intact. In this case, small currents due to the opening of individual channels can be measured in the membrane patch. The whole-cell patch clamp... 

Rubner 0, Kummerhoff PW, Haase H. (1997). [An unusual case of psychosis caused by long-term administration of a scopolamine membrane patch. Paranoid hallucinogenic and delusional symptoms]. 

Cell Remnant Outside-Out Attached Membrane Patch... 

Mogami H., Nakano K., Tepikin A.V., and Petersen O.H. 1997 Ca2+ flow via tunnels in polarized cells recharging of apical Ca2+ stores by focal Ca2+ entry through basal membrane patch. Cell 88, 49—55. 

Figure 4. Open circles, angular dependence of the second-order scattered light intensity (hyper-Rayleigh scattering from 1064 to 532 nm) for a suspension of purple membrane patches of bacteriorhodopsin before any solubilization has taken place. Solid curve best fit to the data by combining the nonlinear hyperpolarizability of retinal with the linear refractive index of the upo-protein.

Therefore, (nonlinear) photonic crystal properties can be attributed to purple membrane patches of bacteriorhodopsin. This is an important finding, since this natural material exhibits photonic bandgap properties without careful and costly engineering, but through self-assembly. In... 

Other biomolecules that are of interest in p.CP are lipids and lipid bilayers. Supported lipid bilayers are very fragile assemblies that are formed by lipids that are organized into two opposing leaflets on hydrophilic surfaces, such as glass or mica substrates. These structures can be also patterned on solid substrates but the p.CP technique differs slightly from the ones that were applied for proteins or DNA. First, the bilayer has to be formed on the oxidized PDMS stamp from the buffer solution by lipid vesicle fusion. Second, printing has to be carried out in water, otherwise the bilayer will lose its structure.99 This method allows efficient and reliable transfer of membrane patches to glass surfaces. 

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