Assessment of pancreatic microcirculation and oxygen delivery by diffuse reflectance spectroscopy in the rat pancreas . Knoefel, Wolfram Trudo, Nikiforos Kollias, David W. Rattner, Norman S. Nishioka, Andrew L. Warshaw. Departments of Surgery, Dermatology and Medicine, Harvard Medical School and Massachusetts General Hospital, Boston MA 02114
APStracts 2:0357A, 1995.
A technique employing diffuse reflectance spectroscopy (DRS) is described to assess and mirror dynamic changes of pancreatic tissue perfusion. An especially designed reflectance spectrophotometer was initially used to derive the quantitative relation between hemoglobin concentration ([Hb]) and reflectance measurements in vitro. Over a wide range of scattering related to the medium in which the measurements were made ([mu]s': 6.5cm-1-13cm-1) a close direct correlation existed with a slope of 0.376 +/- 0.012. In Sprague -Dawley rats under general anesthesia the pancreas was then isolated in situ and perfused with graded infusions of hemoglobin solutions. A correlation, comparable to the in vitro setting, was found between a [Hb] of 0 g/dl and 14 g/dl in the perfusate with slopes of 0.0037 and 0.0035. Changes in perfusion induced by adrenergic drugs produced changes in hemoglobin oxygen saturation (ISO2) and [Hb] which correspond with measured alterations of systemic arterial pressure and aortic blood flow. We conclude that DRS reliably provides data on intrapancreatic ISO2 and [Hb] which can be a valuable tool for minimally invasive on-line evaluation of these aspects of pancreatic perfusion in the rat. This newly designed device is superior to previously used ones in that it analyzes the entire spectrum and therefore can account for changes in scattering that are very likely to occur with pathophysiological alterations such as edema formation. 

Received 14 November 1994; accepted in final form 3 August 1995.
APS Manuscript Number A1159-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 August 1995.