Altered state of cardiac sympathetic nerves during immunologically induced anemia

Cardiac norepinephrine (NE) levels exhibit a marked reduction in rats suffering from hemolytic anemia induced with antibodies against rat red blood cells. Administration of abtiserum via tail vein resulted in a highly reproducible 70% drop in hemoglabin levels by 72 h. At 96 h cardiac NE levels were decreased by 67%; NE levels in vas deferens and submaxillary gland were not decreased. Within 10 days, both hemoglobin and cardiac NE returned to near control levels. Hearts from anemic rats showed a 68% decrease in their ability to accumulate ³H-NE administered in tracer doses at 72 h of anemia. Cardiac NE turnover rates were increased 88% in 72 h anemic animals. These results are consistent with an anemia-induced activation of cardiac sympathetic nerves. Cardiac monoamine oxidase and dopamine-β-hydroxylase activities in whole heart homogenates were similar in control and anemic animals at 72 h. These results suggest that NE depletion is not the result of decreased synthetic capacity of the nerves of degeneration of existing terminals. The data suggest that cardiac NE depletion during anemic stress is associated with the combined effects of increased NE release and a decrease in the effective NE uptake or binding capacity of sympathetic nerves. Anemia-induced depletion may, therefore, be different from the depletion associated with other forms of cardiovascular stress.