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Fluorescence of pyridine nucleotide and flavoproteins as an indicator of substrate oxidation and oxygen demand of the isolated perfused rat kidney

1980; Elsevier BV; Volume: 12; Issue: 1-2 Linguagem: Inglês

10.1016/0020-711x(80)90083-x

1878-6014

H. Franke, Clyde H. Barlow, Britton Chance,

Renal function and acid-base balance

To evaluate the relationship between renal function and mitochondrial redox state the followng photometric techniques were applied to the isolated perfused rat kidney and correlated to changes of experimental conditions: 1. Surface fluorescence of reduced pyridine nucleotides (PN) and oxidized flavoproteins (FP) was recorded simultaneously with a double beam fluorometer. 2. PN-fluorescence was monitored continuously with a DC-fluorometer. 3. Photographs of PN-fluorescence were taken with a large format camera. 1. Since a close relationship exists between FP- and PN-fluorescence during normoxic-anoxic transitions, PN-fluorescence of renal cortex reflects mainly the mitochondrial redox state, while the cytoplasmic signal seems of minor importance. 2. In spite of the high flow rate and the high O2-saturation of the perfusate, renal function during isolated perfusion with dextran is limited by O2-delivery to tissue, as demonstrated by the more oxidized mitochondrial redox state at low perfusion temperatures (28, 20, 14°C) compared to 38°C. 3. Calculated on the base of PN-reduction l-lactate seems to be more utilized for oxidative phosphorylation of kidney cortex than l-glutamine. d-glucose had no effect on PN-fluorescence indicating that d-glucose is not oxidized in renal cortex in large amounts. This finding is supported by the fact that during perfusion with d-glucose in the absence of other substrates renal function was not different from substrate-free perfusion. 4. The PN-fluorescence photographs show the repetitive pattern characteristic for tubular organisation at the kidney surface demonstrating morphological and metabolic heterogeneity.