Mechanisms of cellular photomodification

• Published in: Light activated pest control pp. 24 - 33
• Main Authors: Valenzeno, D.P, Tarr, M
• Format: Conference Proceeding
• Language: English
• Published: Washington, DC : American Chemical Society, 1995 1995
• Subjects: Biological Sciences

An understanding of organismal photosensitization begins with an understanding of sensitized photomodification of cells. Cellular photomodification consists of: 1) transport of the photosensitizer to the site of action, 2) possible binding, aggregation or metabolism, 3) absorption of light at the site, 4) production of energetic intermediate states, 5) reaction with cellular biomolecules, and 6) modification of cellular function. Proteins, lipids, and nucleic acids are susceptible targets, but since many important photosensitizers are lipophilic, membranes are important cellular targets including those of lysosomes and mitochondria. Photosensitized cell death can be either necrotic or apoptotic. An increase in intracellular calcium may trigger either mechanism. We present patch clamp electrophysiological and biochemical results demonstrating that although standard protein channels, including calcium channels, are blocked by photosensitization, a new permeability pathway is induced in cardiac cell membranes. This pathway is selective for cations, shares many properties with the pathway that produces sensitized lysis of erythrocytes, and shows isolated patch currents that suggest that it may be a lipid, rather than a protein, channel.