Effects of hemorrhage and opiate antagonists on adrenal release of neuropeptides in cats

Abstract

Concurrent levels of methionine-enkephalin (ME), neuropeptide Y (NPY), peptide YY (PYY), neurotensin (NT), vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK) and bombesin (BMB) were measured in adrenal vein (AD), femoral vein (FV) and femoral artery (FA) under baseline conditions and during hypotensive hemorrhage (HTH) in halothane anesthetized cats (Group II, n=6) and compared to a non-bled control group (Group I, n=6). Five cats (Group III) received an IV bolus of naltrexone (1 mg/kg) followed by a continuous infusion prior to induction of HTH. A blood volume loss of ∼40% evoked a selective increase in AD levels of ME, NPY, PYY and NT. No differences in regard to hemodynamics and pattern of neuropeptide levels were observed between Group II and Group III. Administration of naloxone (1 mg/kg, IV) in Group I and Group II at the end of the experiment led to a significant increase in MABP in both groups but did not evoke changes in neuropeptide levels. We conclude that adrenal neuropeptide release during hypotensive hemorrhage is not modulated by actions on opiate receptors in the halothane anesthetized cat.