AJP - Regulatory, Integrative and Comparative Physiology, Vol 235, Issue 3 121-R129, Copyright © 1978 by American Physiological Society
Controlled cellular energy conversion in brown adipose tissue thermogenesis
J. M. Horowitz and R. E. Plant
Brown adipose tissue serves as a model system for nonshivering
thermogenesis (NST) since a) it has as a primary physiological function the
conversion of chemical energy to heat; and b) preliminary data from other
tissues involved in NST (e.g., muscle) indicate that parallel mechanisms
may be involved. Now that biochemical pathways have been proposed for brown
fat thermogenesis, cellular models consistent with a thermodynamic
representation can be formulated. Stated concisely, the thermogenic
mechanism in a brown fat cell can be considered as an energy converter
involving a sequence of cellular events controlled by signals over the
autonomic nervous system. A thermodynamic description for NST is developed
in terms of a nonisothermal system under steady-state conditions using
network thermodynamics. Pathways simulated include mitochondrial ATP
synthesis, a Na+/K+ membrane pump, and ionic diffusion through the
adipocyte membrane.
