@entity26 dependent quenching of phosphorescence allows for non-invasive measurements of @entity26 in tissue. We have designed and constructed a novel multi-frequency instrument for measurement of phosphorescence lifetimes and developed algorithms for determining the distribution of @entity26 ( @entity26 histogram) in the microvasculature of tissue with good temporal resolution (Vinogradov et al., 2002, Compar. Biochem. A, these proceedings). This technology, in combination with a new water soluble near infra red phosphor (Oxyphor G2), was used to examine the oxygenation of subcutaneous @entity5 grown on the flank of @entity35 and their response to giving the @entity35 @entity26 or @entity15436 to breathe. Phosphorescence was measured using excitation at 635 nm and emission at >700 nm (the phosphorescence maximum is near 800 nm). The excitation and collection light guides were placed on the surface of the skin of the anesthetized animals separated by approximately 0.8 cm. A 6 x 6 or 7 x 7 grid (approx. 4 cm x 4 cm) was drawn on the flank and @entity26 histograms were measured in each square, providing 'images' of the @entity26 distribution in the tissue. This procedure determines the tissue @entity26 distribution at each position in the grid. Regions of relative @entity519 (associated with the @entity5 ) can be readily localized and the extent of @entity519 quantitatively evaluated.

Measurement of XXXX oxygenation using new frequency domain phosphorometers.

@entity15436 :: ('MESH:C011700', 'Chemical') :: ['carbogen'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'Q7 tumors'] @entity26 :: ('MESH:D010100', 'Chemical') :: ['oxygen', 'Oxygen'] @entity519 :: ('MESH:D000860', 'Disease') :: ['hypoxia'] @entity35 :: ('10116', 'Species') :: ['Buffalo rats', 'rats']
@entity5 :: (MESH:D009369,Disease) :: ['tumor']
