Simultaneous changes of catecholamines and of Leu-enkephalin-like immunoreactivity in plasma and cerebrospinal fluid of cats undergoing acute hemorrhage.

Cats, anesthetized with sodium pentobarbitone, underwent acute hemorrhagic shock by withdrawal of 15 ml blood/kg of body weight. The cerebral ventricular system was perfused with artificial cerebrospinal fluid (CSF). Blood and CSF samples were collected during 2 h, for the analysis of catecholamines (CA) and Leu-enkephalin-like immunoreactivity (LE-ir). The fall of blood pressure immediately after hemorrhage was accompanied by a rise of LE-ir in the CSF and by a decrease of norepinephrine and dopamine below their control values. About half an hour later, the LE-ir returned to its initial low level, while the CA were now markedly elevated. A similar opposite behavior of peptides and CA was observed during subsequent sampling periods, although blood pressure remained constant. These experiments demonstrate an inverse relationship of LE-ir and CA in the CSF, after acute hemorrhagic shock.