From owner-metabolic-reg@net.bio.net Mon Jan 20 22:00:00 1997 Path: biosci!moldev.com!jack_owicki From: jack_owicki@moldev.com (Jack Owicki) Newsgroups: bionet.metabolic-reg Subject: Re: Intelligent drug design Date: 21 Jan 1997 08:36:19 -0800 Organization: BIOSCI International Newsgroups for Molecular Biology Lines: 49 Sender: daemon@net.bio.net Distribution: world Message-ID: NNTP-Posting-Host: net.bio.net Regarding the discussion about the (lack of) emphasis on metabolism in drug discovery..... There is one method fairly widely in use in the pharmaceutical industry (and, to some extent, in academia) that relies on monitoring energy metabolism in living cells. It's called microphysiometry, and it employs a semiconductor-based pH sensor in a flow chamber (volume ~3 uL, flow rate ~1 uL/s, ~100,000 cells) to detect the rate at which the cells acidify their environment. The pH excursions are no more than 0.1 unit, and cells (eukaryotic or prokaryotic; adherent or nonadherent) can be kept happy for many hours. Time resolution, based on fluid mixing and the time to make an acidification-rate measurement, is about 1 minute. This measurement of the rate of production of acidic products of energy metabolism (CO2, lactic acid) is one empirical index of the rate of energy metabolism. While it has obvious limitations in terms of mechanistic interpretations, it has proven a relatively general way of detecting physiological changes in cells when they are exposed to some test compound. It's especially useful for detecting receptor activation, fairly independently of the mechanism of signal transduction. In many cases, receptor activation leads to 10% to 100% changes in acidification rate, usually transient but sometimes sustained. Anyone interested in more information can check the following references: *Parce et al. (1989) "Detecting of cell-affecting agents with a silicon biosensor," Science 242:243. *McConnell et al. (1992) "The Cytosensor microphysiometer: Biological applications of silicon technology," Science 257:1906. *Owicki et al. (1994) "The light-addressable potentiometric sensor: Principles and biological applications," Ann. Rev. Biophys. Biomol. Struct. 23:87. Disclaimer: I do R&D at the company that sells the microphysiometer instrument. ------------------------------------------------------------ John C. Owicki, Ph.D. Associate Technical Director & FLIPR Applications Manager Molecular Devices Corporation 1311 Orleans Drive Sunnyvale, CA 94089 E-mail: jack_owicki@moldev.com Phone: (408) 747-3514; Fax: (408) 747-3601 .