V. Parpura et Pg. Haydon, UV photolysis using a micromanipulated optical fiber to deliver UV energy directly to the sample, J NEUROSC M, 87(1), 1999, pp. 25-34
UV photolysis of caged molecules is a powerful method for studying cellular
signaling. However, UV energy is often delivered through the microscope ob
jective which can make certain experiments difficult. We have evaluated the
utility of delivering UV pulses directly to the sample through an optical
fiber. Visible (635 nm) and UV (337 nm) lasers were coupled into a UV trans
mitting optical fiber which was micromanipulated over the sample under inve
stigation. Positioning of the fiber, and thus the photolysis beam, was achi
eved using the visible laser which acted much like a flashlight. By control
ling the size of the optical fiber it is also possible to control the area
of the sample which is exposed to UV light. After positioning the fiber we
demonstrate that the UV beam exiting the optical fiber reliably photolysed
NP-EGTA that had been loaded into cells, resulting in an elevation of intra
cellular calcium. Additionally, caged norepinephrine in the bathing saline
was photo-released to activate receptor-operated calcium signaling pathways
. Since the delivery of the UV energy is independent of microscope configur
ation, this approach can be readily incorporated into wide-field fluorescen
ce imaging, confocal microscopy and electrophysiological applications. (C)
1999 Elsevier Science B.V. All rights reserved.