Effects of long-term dietary restriction on cardiovascular function and plasma catecholamines in the rat.

To examine the relationship between heart function and plasma catecholamines upon food restriction, normal adult rats were fed 12 g or 6 g food/day for 14 days and 12 g food/day for 28 days. Food-restricted rats exhibited bradycardia, hypotension, and decreased rates of cardiac contraction (+dP/dt) as well as relaxation (-dP/dt) at 14 (12 or 6 g food/day) and 28 (12 g food/day) days. Plasma norepinephrine and epinephrine levels were significantly elevated in the 6 g food/day group at 14 days, whereas in the 12 g food/day group, plasma norepinephrine was elevated at 14 days but was significantly decreased at 28 days. Heart norepinephrine and epinephrine concentrations were elevated at both 14 and 28 days of food restriction in the 12 g food/day group as well as at 14 days in the 6 g food/day group. Thus, dietary restriction appears to result in depressed indices of heart function, while the circulating levels of catecholamines were elevated at early stages.