Advances in vibrating probe techniques

PROTOPLASMA ◽  
1982 ◽  
Vol 113 (2) ◽  
pp. 89-96 ◽  
Author(s):  
A. Dorn ◽  
M. H. Weisenseel
Keyword(s):  
Vibrating Probe

The extracellular electrical current pattern and its variability in vitellogenic Drosophila follicles

1986 ◽  
Vol 81 (1) ◽  
pp. 189-206 ◽  
Author(s):  
J. Bohrmann ◽  
A. Dorn ◽  
K. Sander ◽  
H. Gutzeit
Keyword(s):  
Juvenile Hormone ◽  
Current Density ◽  
Developmental Stages ◽  
Electrical Current ◽  
Posterior Pole ◽  
The Other ◽  
Follicular Epithelium ◽  
Nurse Cells ◽  
Vibrating Probe ◽  
Current Pattern

We determined the extracellular electrical current pattern around Drosophila follicles at different developmental stages (7–14) with a vibrating probe. At most stages a characteristic pattern can be recognized: current leaves near the oocyte end of the follicle and enters at the nurse cells. Only at late vitellogenic stages was an inward-directed current located at the posterior pole of many follicles. Most striking was the observed heterogeneity both in current pattern and in current density between follicles of the same stage. Different media (changed osmolarity or pH, addition of cytoskeletal inhibitors or juvenile hormone) were tested for their effects on extrafollicular currents. The current density was consistently influenced by the osmolarity of the medium but not by the other parameters tested. Denuded nurse cells (follicular epithelium locally stripped off) show current influx, while an accidentally denuded oocyte produced no current. Our results show that individual follicles may be electrophysiologically different, though their uniform differentiation during vitellogenesis does not reflect such heterogeneity.

Changes in transcellular ionic currents associated with polar lobe formation in embryos of Bithynia

Development ◽  
1991 ◽  
Vol 112 (2) ◽  
pp. 451-459
Author(s):  
D. Zivkovic ◽  
R. Dohmen
Keyword(s):  
Ionic Currents ◽  
Vibrating Probe ◽  
Polar Lobe ◽  
Probe Technique

Using the vibrating probe technique, we have measured currents ranging from 0.05 to 3.00mAcm-2 around polar-

Segregation of gastric Na and Cl transport: a vibrating probe and microelectrode study

1986 ◽  
Vol 251 (4) ◽  
pp. C643-C648 ◽  
Author(s):  
J. R. Demarest ◽  
C. Scheffey ◽  
T. E. Machen
Keyword(s):  
Gastric Mucosa ◽  
Cell Membrane ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Cell Types ◽  
Open Circuit ◽  
Membrane Potentials ◽  
Vibrating Probe ◽  
Zero Current ◽  
Mucosal Side

The short-circuit current (Isc) of resting Necturus gastric mucosa (approximately 20 microA/cm2) can be attributed to the algebraic sum of the net Cl- secretion and amiloride-inhibitable net Na+ absorption. We have attempted to identify the cell types [surface epithelial cells (SCs) or oxyntic cells (OCs)] responsible for the transport of these ions in Necturus gastric mucosa using microelectrodes (ME) and a vibrating probe (VP). Mucosae were mounted horizontally in an open-topped Plexiglas chamber either serosal side up for basolateral ME impalements of OCs or mucosal side up for apical impalements of SCs and VP measurements. Cell impalements were made under open-circuit conditions, and VP measurements were performed under short-circuit conditions. Impalements of OCs indicate that neither the ratio of their apical to basolateral cell membrane resistances (Ra/Rb = 1.3 +/- 0.2) nor their cell membrane potentials were affected by 10(-6) M mucosal amiloride. In contrast, impalements of SCs indicate that amiloride increased their Ra/Rb from 3.5 +/- 0.2 to 15.6 +/- 1.8 and hyperpolarized both cell membrane potentials by greater than 20 mV. VP measurements showed that the amiloride-induced change in the current from SCs (5.6 microA/cm2) accounted for the amiloride-induced change in the Isc (5.5 microA/cm2). A non-zero current (4.4 +/- 1.0 microA/cm2) measured over SCs in the presence of amiloride was due to contamination from current arising from the gastric crypts that contain the OCs.(ABSTRACT TRUNCATED AT 250 WORDS)

The waveform separation of displacement current and tunneling current using a scanning vibrating probe

2001 ◽  
Vol 393 (1-2) ◽  
pp. 204-209 ◽  
Author(s):  
Yutaka Majima ◽  
Setsuri Uehara ◽  
Tomohiko Masuda ◽  
Atsushi Okuda ◽  
Mitsumasa Iwamoto
Keyword(s):  
Tunneling Current ◽  
Displacement Current ◽  
Vibrating Probe

Tunneling Current-Distance Characteristic of Scanning Vibrating Probe / 1-Alkanethiol Self-Assembled Monolayer (SAM) / Au (111) Structure

2003 ◽  
Vol 782 ◽  
Author(s):  
Yuhsuke Yasutake ◽  
Yasuo Azuma ◽  
Kouhei Nagano ◽  
Yutaka Majima
Keyword(s):  
Tunneling Current ◽  
Self Assembled Monolayers ◽  
Vibrating Probe ◽  
Self Assembled Monolayer ◽  
Contact Conductance ◽  
Decay Constants ◽  
Assembled Monolayers ◽  
Probe Voltage ◽  
Self Assembled

ABSTRACTWe report measurements of the tunneling current – distance (I-d) dependence above alkanethiol self-assembled monolayers (SAMs) on Au (111) substrates with high probe voltage. From the semilogarithmic I-d plots of hexanethiol and octanethiol SAMs, a kink in the tunneling current slopes is clearly observed, which shows the point where the STM tip contacts the end of the SAMs. The conductance decay constants of the vacuum layer and the alkanethiol SAMs are estimated from the tunneling current slopes. We also discuss the contact conductance of alkanethiol SAMs.

scholarly journals Regional distribution of the Na+ and K+currents around the crystalline lens of rabbit

2002 ◽  
Vol 282 (2) ◽  
pp. C252-C262 ◽  
Author(s):  
Oscar A. Candia ◽  
Aldo C. Zamudio
Keyword(s):  
Polar Region ◽  
Regional Distribution ◽  
Crystalline Lens ◽  
Theoretical Models ◽  
Vibrating Probe ◽  
Positive Currents ◽  
Posterior Direction ◽  
Net Flows ◽  
Lens Surface ◽  
K Currents

Early studies described asymmetrical electrical properties across the ocular lens in the anterior-to-posterior direction. More recent results obtained with a vibrating probe indicated that currents around the lens surface are not uniform by showing an outwardly directed K+ efflux at the lens equator and Na+ influx at the poles. The latter studies have been used to support theoretical models for fluid recirculation within the avascular lens. However, the existence of a nonuniform current distribution in the lens epithelium from the anterior pole to the equator has never been confirmed. The present work developed a modified short-circuiting technique to examine the net flows of Na+ and K+ across arbitrarily defined lens surface regions. Results indicate that passive inflows of Na+ occur at both the anterior polar region and posterior lens surface, consistent with suggestions derived from the vibrating probe data, whereas K+ efflux plus the Na+-K+ pump-generated current comprise the currents at the equatorial surface and an area anterior to it. Furthermore, Na+-K+ pump activity was absent at the posterior surface and its polar region in all lenses examined, as well as from the anterior polar region in most lenses. The latter unexpected observation suggests that the monolayered epithelium, which is confined to the anterior surface of the lens, does not express an active Na+-K+ pump at its anterior-most aspect. Nevertheless, this report represents the first independent confirmation that positive currents leave the lens around the equator and reenter across the polar and posterior surfaces.

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