Argon laser microirradiation of mitochondria in rat myocardial cells in tissue culture. VII. fibrillation in ventricle and auricle cells

A history of laser scissors (microbeams)

This introductory chapter reviews the history of microbeams starting with the original UV microbeam work of Tchakhotine in 1912 and covers the progress and application of microbeams through 2006. The main focus of the chapter is on laser "scissors" starting with Marcel Bessis' and colleagues work with the ruby laser microbeam in Paris in 1962. Following this introduction, a section is devoted to describing the different laser microbeam systems and then the rest of the chapter is devoted to applications in cell and developmental biology. The approach is to focus on the organelle/structure and describe how the laser microbeam has been applied to studying its structure and/or function. Since considerable work has been done on chromosomes and the mitotic spindle (Section V.A and C), these topics have been divided in distinct subsections. Other topics discussed are injection of foreign DNA through the cell membrane (optoporation/optoinjection), cell migration, the nucleolus, mitochondria, cytoplasmic filaments, and embryos fate-mapping. A final technology section is devoted to discussing the pros and cons of building/buying your own laser microbeam system and the option of using the Internet-based RoboLase system. Throughout the chapter, reference is made to other chapters in the book that go into more detail on the subjects briefly mentioned.

In vitro photosensitization I. Cellular uptake and subcellular localization of mono-L-aspartyl chlorin e6, chloro-aluminum sulfonated phthalocyanine, and photofrin II

The mechanisms of cellular uptake, subcellular localization, and cellular retention kinetics of the photosensitizers photofrin II (PfII), mono-L-aspartyl chlorin e6 (MACE), and chloro-aluminum sulfonated phthalocyanine (CASPc) are reported in this paper. Each photosensitizer's cellular uptake mechanism was determined by preferentially inhibiting endocytosis by chilling cells to 2 degrees C, while allowing diffusion across the membrane. Subcellular localization was studied by computer-enhanced low-light level video fluorescence microscopy, while flow cytometry was used to determine uptake and retention kinetics. The results indicate that PfII enters the cell primarily by diffusion across the membrane, whereas MACE and CASPc enter the cell through endocytosis.

Alteration of membrane electrical activity in rat myocardial cells following selective laser microbeam irradiation

Laser microirradiation of neonatal rat (1 to 2-day-old) ventricular cells in tissue culture results in overt changes in contractility. The intracellular study of their ongoing electrical activity prior to, during, and after laser microirradiation demonstrates that definite membrane alteration occurs concomitantly with induced contractile responses. Although all ventricular cells are depolarized by laser microirradiation, the ultimate response elicited seems to differ according to the type of myocardial cell impaled. Typical fibrillation potentials were induced mainly in pacemaker cells.