Patch-clamp experiments

The isolated oocytes are still surrounded by the vitelline membrane, an inner glycoprotein matrix layer (Yao et al., 2000). This layer does not interfere with whole-cell recording experiments. It can be removed manually however, for patch-clamp experiments requiring the formation of high-resistance seals. 

Polar Cell Systems for Membrane Transport Studies Direct current electrical measurement in epithelia steady-state and transient analysis, 171, 607 impedance analysis in tight epithelia, 171, 628 electrical impedance analysis of leaky epithelia theory, techniques, and leak artifact problems, 171, 642 patch-clamp experiments in epithelia activation by hormones or neurotransmitters, 171, 663 ionic permeation mechanisms in epithelia biionic potentials, dilution potentials, conductances, and streaming potentials, 171, 678 use of ionophores in epithelia characterizing membrane properties, 171, 715 cultures as epithelial models porous-bottom culture dishes for studying transport and differentiation, 171, 736 volume regulation in epithelia experimental approaches, 171, 744 scanning electrode localization of transport pathways in epithelial tissues, 171, 792. 

Dudanova I, Sedej S, Ahmad M et al (2006) Important contribution of a-neurexins to Ca2+-triggered exocytosis of secretory granules. J Neurosci 26 10599-613 Fesce R, Segal JR, Ceccarelli B et al (1986) Effects of black widow spider venom and Ca2+ on quantal secretion at the frog neuromuscular junction. J Gen Physiol 88 59-81 Filippov AK, Tertishnikova SM, Alekseev AE et al (1994) Mechanism of a-latrotoxin action as revealed by patch-clamp experiments on Xenopus oocytes injected with rat brain messenger RNA. Neuroscience 61 179-89... 

There is also evidence from inside-out patch-clamp experiments that the human and canine KCa3.1 channels respectively expressed in Xenopus leavis oocytes and... 

Schlatter E (1993) Effect of various diuretics on membrane voltage of macula densa cells. Whole-cell patch-clamp experiments. Pfliigers Arch Eur J Physiol 423 74-77... 

There are four protocols for performing the patch-clamp experiment (Figure 5). These are listed as follows ... 

Consequently, larger spheres require a smaller pressure differential to maintain a given membrane tension than smaller spheres, and vice versa. The magnitudes of the pressure differential required to generate specific levels of membrane tension can be estimated from the following considerations. For a membrane with a radius of curvature = 3 pm (typical of the dimensions in a patch clamp experiment), application of 0.1 atm pressure (where 1 atm = 760 mm Hg = 1.013 x 106 dyn cm-2) corresponds to a = 15 dyn cm-1. The maximum applied pressure depends on the limit at which the patches break ( 20-30 dyn cm-1) and the curvature of the membrane, but is typically 0.2 atm. 

Patch-clamp experiments with the tubules of the similar octapeptide cyclo-[(Trp-D-Leu)3-Gln-D-Leu] in phospholipid bilayers indicate short-lived... 

Figure 13.14 Observing single channels. The results of a patch clamp experiment revealing a single ion channel undergoing transitions between closed and open states.

One of the key features of ABA enhancement of Ik,oui is that it persists even when cytosolic Ca" concentrations are buffered to low levels by the inclusion of EGTA in the patch pipette solution during whole cell reeording. This suggests that elevated [Ca ],., is not involved in the activation of Ik.oui t>y ABA. Indeed, when [Ca ], is experimentally elevated from approximately 2 nM to 200 nM in whole-cell patch clamp experiments, current through outward K channels is reduced [72], an effect which would oppose stomatal closure. At higher [Ca ],.y,s, outward current shows little Ca -sensitivity [23]. More recently, it has been shown that Ik oui sensitive to cytoplasmic pH. Its regulation by pH has consequences for ABA-induced closure, and will be discussed in Section... 

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