A new sample isolation procedure for microchemical analysis of functional liver cell heterogeneity.

In conjunction with the investigation of intercellular compartmentation of liver carbohydrate metabolism, a new procedure for isolation of tissue samples from freeze-dried cryosections was developed. It was designed to permit assessment of functional differences between sinusoids of portal and septal origin, and to extend investigation of liver cell heterogeneity along sinusoids to the level of the structural-functional unit. Application of this procedure, together with microchemical assays of high analytical sensitivity, enabled measurement of 50 individual glucose and glucose-6-P values in a single cross-sectional area of about 0.75 mm2 of a liver unit. Preliminary results on the distribution of glucose and glucose-6-P indicated that, in a state of overall glucose release glucose levels were significantly higher in the center than in the periphery of the unit. Overall glucose release by the liver resulted from both release and uptake of glucose along sinusoids. Glucose-6-P was highest in the periphery and decreased toward the center. Microchemical data, furthermore, indicated possible functional heterogeneity of sinusoids, insofar as both glucose and glucose-6-P gradients were steeper in "portal-central" than in "septal-central" sinusoids.