Suppression of sympathetic nervous system during fasting.

Two days of fasting in rats significantly reduces the turnover of norepinephrine in the heart. In contrast to the effects of ganglionic blockade in fed controls, similar blockade in fasted animals is without significant effect on [3H]-norepinephrine retention or endogenous norepinephrine in the heart. These data are consistent with suppression of centrally mediated sympathetic activity in the fasted state. The decrease in norepinephrine turnover during fasting is completely reversed by 1 day of refeeding.