An important goal in many physiological studies is to obtain an understanding of the mechanisms of communication between cells and organs, which allow the integrated functioning of the intact organism.

A major component in these pathways is the sympathetic nervous system. This system controls many acute and longterm responses of the organism to an external challenge. To understand the effects of sympathetic nervous stimulation on peripheral organs has been a goal for many years in the Institute's department of physiology. The majority of projects in the department relate to this question and address more directly the role of the sympathetic neurotransmitter noradrenaline in bringing about acute and chronic responses in responding cells.

As a model tissue, the mammalian brown adipose tissue has been selected. This tissue is ideal in many respects as it is a tissue of exceptionally high metabolic responsiveness, is massively sympathetically innervated and can be induced in the intact organism to hypertrophy and atrophy through the simple physiological stimulus of changing environmental temperature.

Brown adipose tissue in itself is also physiologically interesting as it is the only important organ for regulatory heat production in the mammalian neonate. It contributes also significantly to thermogenesis in small, coldexposed mammals and potentially has a role in regulating energy expenditure also in larger mammals.

We have developed a cell culture system in which we can follow the growth and differentiation of fibroblast-like preadipocytes to fully differentiated adipocytes andw can mimic the physiological challenge in an in -vitro system. Many of our studies involve analysis of the signal transduction pathways through which noradrenaline achieves its intracellular effects.