Electrolysis: processes – compositions used therein – and methods – Electrolytic analysis or testing – Using semipermeable membrane
Patent
1997-04-25
2000-05-16
Noland, Thomas P.
Electrolysis: processes, compositions used therein, and methods
Electrolytic analysis or testing
Using semipermeable membrane
204415, G01N 2733
Patent
active
060632607
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to apparatus for carrying out patch clamp technique utilized to study ion transfer channels in biological membranes, and more particularly refers to such patch clamp apparatus having high through-put and utilizing only small test samples of compounds, only small amounts of liquid carrier, and capable of carrying out many tests in a short period of time with an individual membrane patch. The invention more broadly refers to a novel electrophysiology drug handling and application set up for screening of chemical substances or compounds, which provides high throughput, and which requires only low volume of solutions and samples to be tested. The invention also comprises several methods for utilizing the apparatus of the invention.
2. Prior Art
The general idea of electrically isolating a patch of membrane using a micropipette and studying the ion channels in that patch under voltage-clamp conditions was outlined by Neher, Sakmann, and Steinback in "The Extracellular Patch Clamp, A Method For Resolving Currents Through Individual Open Channels In Biological Membranes", Pflueger Arch. 375; 219-278, 1978. They found that, by pressing a pipette containing acetylcholine (ACH) against the surface of a muscle cell membrane, they could see discrete jumps in electrical current that were attributable to the opening and closing of ACH-activated ion channels. However, they were limited in their work by the fact that the resistance of the seal between the glass of the pipette and the membrane (10-50 M.OMEGA.) was very small relative to the resistance of the channel (.about.10 G.OMEGA.). The electrical noise resulting from such a seal is inversely related to the resistance and was large enough to obscure the currents through ion channels, the conductances of which are smaller than that of the ACH channel. It also prohibited the clamping of the voltage in the pipette to values different from that of the bath due to the large currents through the seal that would result.
It was then discovered that by fire polishing the glass pipettes and applying gentle suction to the interior of the pipette when it made contact with the surface of the cell, seals of very high resistance (1-100 G.OMEGA.) could be obtained, which reduced the noise by an order of magnitude to levels at which most channels of biological interest can be studied and greatly extended the voltage range over which these studies could be made. This improved seal has been termed a "giga-seal", and the pipette has been termed a "patch pipette". For their work in developing the patch clamp technique, Neher and Sakmann were awarded the 1991 Nobel Prize in Physiology and Medicine.
Ion channels are transmembrane proteins, which catalyze transport of inorganic ions across cell membranes. The ion channels participate in processes as diverse as generating and timing of action potentials, synaptic transmission, secretion of hormones, contraction of muscles, etc. Many drugs exert their specific effects via modulation of ion channels. Examples are antiepileptic compounds like phenytoin and lamotrigine, which block voltage dependent Na.sup.+ -channels in the brain, antihypertensive drugs like nifedipine and diltiazem, which block voltage dependent Ca.sup.2+ -channels in smooth muscle cells, and stimulators of insulin release like glibenclamide and tolbutamide, which block an ATP-regulated K.sup.+ -channel in the pancreas. In addition to chemically induced modulation of ion-channel activity, the patch clamp technique has enabled scientists to perform voltage dependent channel manipulations. These techniques include adjusting the polarity of the electrode in the patch pipette and altering the saline composition to moderate the free ion levels in the bath solution.
The patch clamp technique represents a major development in biology and medicine, since this technique allows measurement of ion flow through single ion channel proteins, and also allows the study of the single ion channel responses to drugs.
REFERENCES:
patent: 4128456 (1978-12-01), Lee et al.
patent: 4713974 (1987-12-01), Stone
patent: 4889691 (1989-12-01), Argentieri
patent: 5364521 (1994-11-01), Zimmermann
patent: 5424037 (1995-06-01), Zimmermann et al.
Patent Abstracts of Europe (DE 04305405 C1) May 26, 1994 (Assignee: Hering) .
Christophersen Palle
Olesen S.o slashed.ren-Peter
NeuroSearch A/S
Noland Thomas P.
LandOfFree
Patch clamp apparatus and technique having high throughput and l does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Patch clamp apparatus and technique having high throughput and l, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Patch clamp apparatus and technique having high throughput and l will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-255696