Tag perforated [7 articles]

Abstract

We present experimental procedures describing the creation of perforated patches by use of amphotericin B. In 13 different cellular preparations, access resistances below 10 M omega were achieved and with blunt electrode tips, access resistances of 3-4 M omega were possible. In addition to using the techniques to measure whole cell currents, we have used them to measure single channel currents in a new "outside-out patch" preparation and we have utilized them to measure the resting voltage of epithelial monolayers. We ...

Abstract

Defects in myocyte contraction and relaxation are key features of human heart failure. Sodium/calcium exchanger-mediated contribution to contraction and relaxation were separated from other mechanisms [L-type calcium current, sarco(endo)plasmic reticulum (SR) Ca2+-ATPase] based on voltage, temperature, and selective blockers. Rod-shaped left ventricular myocytes were isolated from failed human explants (n = 29) via perfusion with collagenase-containing Krebs solution. Action potentials using perforated patch and contractions using an edge detector were recorded at 0.5-1.5 Hz in Tyrode solution at 25degreesC and 37degreesC. ...

Abstract

Action potential duration (APD) restitution properties and repolarization alternans are thought to be important arrhythmogenic factors. We investigated the role of intracellular calcium (Ca2+i) cycling in regulating APD restitution slope and repolarization (APD) alternans in patch-clamped rabbit ventricular myocytes at 34 to 36degreesC, using the perforated or ruptured patch clamp techniques with Fura-2-AM to record Ca2+i. When APD restitution was measured by either the standard extrastimulus (S1S2) method or the dynamic rapid pacing method, the maximum APD restitution slope exceeded 1 ...

Abstract

Abstract   Perforated patch recording with nystatin, amphotericin B and gramicidin can be more difficult in the hands of some investigators than others. In addition, it is difficult to introduce low molecular weight substances such as dyes into the cytoplasm in such experiments. We have determined that β-escin represents a convenient, easy-to-use alternative to less water-soluble ionophores. ...

Abstract

The conventional l type Ca2+ channel current (ICa.L) was measured in single atrial and ventricular myocytes, with a new whole-cell recording technique using an ionophore, nystatin. The membrane of a cell-attached patch was gradually permeabilized by nystatin (100–200 gg/ml), added to the pipette solution, within 2–5 min after formation of a GO-seal. The electrical activity of the cells was measured through the pipette. ICa.L, measured with the nystatin-whole cell recording technique, did not exhibit the so-called “run-down” phenomenon for up to ...

Abstract

Whole cell currents were recorded in single myocytes dissociated from guinea pig ventricles by the patch-clamp technique. The addition of 0.1 mg/ml gramicidin D, a cation-selective ionophore, into the pipette solution induced a gradual spontaneous perforation of the patch membrane under a conventional cell-attached configuration. The access resistance, measured at approximately 12 min after formation of a gigaohm seal, was 9.2 +/- 1.5 M omega (n = 12). The perforated patch membrane exhibited ionic selectivity for various monovalent cations, with a ...