Plasma catecholamines: Exaggerated elevation is associated with stress susceptibility

The ability to survive acute stress differs markedly between individual rats. In order to determine whether ability to survive stress is correlated with aberrations of the sympathoad-renomedullary response, we measured plasma and tissue catecholamines (CA's) and blood glucose before, during, and for 5 hr after footshock stress. Splenic weights and liver glycogen were measured at sacrifice. Rats that survived the post-stress period (survivors) were compared to rats that did not survive (lethalities). Our results revealed a malignant rise of plasma CA's in lethalities beginning at stress onset and continuing until death. Plasma CA's in lethalities during stress were over 200% of those in survivors, whereas tissue CA's were reduced in both groups. Paradoxically, responses to circulating and neuronal CA's appeared to be diminsished in lethalities. Lethalities, but not survivors, became profoundly hypoglycemic after stress, in spite of their elevated plasma CA's. Likewise, evidence of significant splenic contraction was absent in lethalities. Thus, elevated plasma CA concentrations and reduced target organ responsiveness are associated with stress-induced lethality.