Label-Free Calcium Imaging in Ischemic Retinal Tissue by TOF-SIMS

• Published in: Biophysical journal Vol. 94; no. 10; pp. 4095 - 4102
• Main Authors: Kim, Jin Hyoung, Kim, Jeong Hun, Ahn, Bum Ju, Park, Jae-Hwan, Shon, Hyun Kyong, Yu, Young Suk, Moon, Dae Won, Lee, Tae Geol, Kim, Kyu-Won
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.05.2008; Biophysical Society; The Biophysical Society
• Subjects: Animals; Biophysics; Calcium; Calcium - metabolism; Cells; Ions; Ischemia - metabolism; Ischemia - pathology; Male; Mice; Mice, Inbred C57BL; Retinal Vessels - metabolism; Retinal Vessels - pathology; Scientific imaging; Spectrometry, Mass, Electrospray Ionization - methods; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; Spectroscopy, Imaging, Other Techniques; Staining and Labeling; Tissue Distribution
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1529/biophysj.107.119800

The distribution and movement of elemental ions in biologic tissues is critical for many cellular processes. In contrast to chemical techniques for imaging the intracellular distribution of ions, however, techniques for imaging the distribution of ions across tissues are not well developed. We used time-of-flight secondary ion mass spectrometry (TOF-SIMS) to obtain nonlabeled high-resolution analytic images of ion distribution in ischemic retinal tissues. Marked changes in Ca2+ distribution, compared with other fundamental ions, such as Na+, K+, and Mg2+, were detected during the progression of ischemia. Furthermore, the Ca2+ redistribution pattern correlated closely with TUNEL-positive (positive for terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate nick end-labeling) cell death in ischemic retinas. After treatment with a calcium chelator, Ca2+ ion redistribution was delayed, resulting in a decrease in TUNEL-positive cells. These results indicate that ischemia-induced Ca2+ redistribution within retinal tissues is associated with the order of apoptotic cell death, which possibly explains the different susceptibility of various types of retinal cells to ischemia. Thus, the TOF-SIMS technique provides a tool for the study of intercellular communication by Ca2+ ion movement.