ABSTRACT

This chapter focuses on the differences between cell types, along with a consideration of species specificity. Most fat cells are known as white adipose tissue which can be broadly divided between subcutaneous and visceral fat, although this itself represents a simplification. The brown adipose tissue has long been known to contribute to non-shivering thermogenesis, arousal from hibernation, and heat production in the newborn, including humans. The ratio of lactate to pyruvate thus presented to peripheral tissues can be considered to be a reflection of the NAD/NADH of the tissue of origin. Supplying the liver cells with glycerol produces a very high concentration of cytosolic NADH, attenuating glycolytic flow through GAPDH. Dihydroxyacetone and glycerol differ only by a two-electron reduction. Dihydroxyacetone is certainly a sugar, and while not present in significant quantities physiologically, is also a gluconeogenic substrate. As most galactose arises from milk products as lactose, it is unlikely that a problem similar to fructose arises.