Table I.

Redox State of NAD(P)H, R_PN, and Fluorescent Flavoproteins, R_FP, in Saponin-permeabilized Muscle Fibers from m. quadriceps Determined by Laser Fluorometry and Fluorescence Microscopy

		RPN		RFP
		(%)		(%)
Fiber bundles		35 ± 3		26 ± 9
		n = 8		n = 8
High fluorescent fibers (oxidative)		32 ± 3		33 ± 11
		n = 5		n = 5
Low fluorescent fibers (glycolytic)		46 ± 8		30 ± 13
		n = 5		n = 5

The redox states, R, are given in % of the fluorescence change between the fully oxidized state, F _endo (in the absence of substrates), and the completely reduced state, F _KCN (in the presence of substrates and 4 mM cyanide). They were determined from the fluorescence values, F _ADP, in the presence of 1 mM ADP and the substrate combination 1 mM octanoylcarnitine + 5 mM malate (experimental protocol of Figs. 1 and 3) using the following formulas: R _PN = (F _ADP − F _endo)/(F _KCN − F _endo) · 100 R _FP = (F _endo − F _ADP)/(F _endo − F _KCN) · 100. In the microscopic determinations, the average gray values of high and low fluorescent single fibers in the different metabolic states were used for the calculation of the fluorescence changes. The reproducibility and linearity of the image acquisition was verified using fluorescence standards (uranyl filter glass GG17, Schott). n indicates the number of different animals.