Please use this identifier to cite or link to this item:
http://hdl.handle.net/1942/3659
Title: | MEASUREMENT OF INTRACELLULAR AND LUMINAL K+ CONCENTRATIONS IN A MALPIGHIAN TUBULE (FORMICA) - ESTIMATE OF BASAL AND LUMINAL ELECTROCHEMICAL K+ GRADIENTS | Authors: | LEYSSENS, Anne VAN KERKHOVE, Emmy ZHANG, SL WELTENS, R STEELS, Paul |
Issue Date: | 1993 | Publisher: | PERGAMON-ELSEVIER SCIENCE LTD | Source: | JOURNAL OF INSECT PHYSIOLOGY, 39(11). p. 945-958 | Abstract: | Cellular and luminal K+ concentrations were measured in different bath K+ concentrations using double-barrelled K+-selective electrodes. The electrochemical gradient for K+ across the basal and the apical cell membrane was estimated. The experiments were performed in two Cl- concentrations. In control Ringer (41 mM K+ and 57 mM Cl-) cell K+ was 82 mM and luminal K+ was 119 mM. On lowering bath K+ to 4 mM or increasing it to 90 mM cell K+ and to a lesser extent luminal K+ followed: cell K+ changed to 29 and 90 mM and luminal K+ to 106 and 132 mM, respectively. In a 143 mM Cl- Ringer solution cellular and luminal K+ concentration showed a similar change with the basal K+ concentration. The basal membrane potential difference was almost equal to the equilibrium potential for K+ in all bath K+ and Cl- concentrations tested and the estimated electrochemical gradient for K+ across the basal membrane was very small (inward, zero, or even outward in low bath K+). It tended to become more inward as the bath K+ increased. The methods for estimating such a small gradient and the idea of passive K+ uptake through K+ channels across this barrier was critically evaluated. The large transepithelial electrochemical gradient against which K+ was transported was primarily situated in the apical membrane. This gradient decreased as the bath K+ was elevated (and fluid secretion accelerated): an increase in the bath K+ reduced both the electrical and concentration step to be overcome for K+ secretion across the apical membrane. A double role for the bath K+ in the regulation of K+ secretion is proposed. | Notes: | LIMBURGS UNIV CENTRUM,PHYSIOL LAB,B-3590 DIEPENBEEK,BELGIUM. | Keywords: | MALPIGHIAN TUBULES; K+ TRANSPORT; ION-SELECTIVE MICROELECTRODES; TRANSMEMBRANE GRADIENTS | Document URI: | http://hdl.handle.net/1942/3659 | DOI: | 10.1016/0022-1910(93)90004-B | ISI #: | A1993MK10700004 | Type: | Journal Contribution |
Appears in Collections: | Research publications |
Show full item record
SCOPUSTM
Citations
22
checked on Sep 2, 2020
WEB OF SCIENCETM
Citations
25
checked on Apr 22, 2024
Page view(s)
66
checked on Oct 30, 2023
Google ScholarTM
Check
Altmetric
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.