Opioid peptides attenuate blood pressure increase in acute respiratory failure

Plasma opioid peptides, norepinephrine. atrial natriuretic factor (ANF) and blood pressure (BP) were assessed in 24 chronic obstructive pulmonary dise ase patients with acute respiratory failure. Hypoxemic-hypercapnic patients had high BP, beta -endorphin. Met-enkephalin and dynorphin B, whereas hypo xrmic-normocapnic and hypoxemic-hypocapnic patients showed normal BP, high beta -endorphin, and normal Met-enkephalin and dynorphin B. Norepinephrine and ANF were high in all patients, particularly in hypoxemic-hypercapnic pa tients. Infusion with the opioid antagonist naloxone hydrochloride signific antly increased systolic blood pressure (SBP) in hypoxemic-hypercapnic (182 .0 +/- 3.2 versus 205.1 +/- 3.0 mmHg; P < 0.01), hypoxemic-normocapnic (149 .3 +/- 1.8 versus 169.1 +/- 1.7 mmHg; P < 0.01) and hypoxemic-hypocapnic (1 47.3 +/- 1.3 versus 166.8 +/- 2.2 mmHg; P < 0.01) patients, norepinephrine in hypoxemic-hypercapnic patients (3583.2 +/- 371.8 versus 5371.3 +/- 260.0 fmol/ml; P < 0.01), and reduced ANF in hypoxemic-normocapnic (18.3 +/- 0.8 versus 11.9 +/- 1.0 fmol/ml; P < 0.05) and hypoxemic-hypocapnic (18.1 +/- 1.2 versus 12.1 +/- 2.1 fmol/ml; P < 0.05) patients. These results indicate that the endogenous opioid system attenuates SEP responses in acute respir atory failure by affecting norepinephrine or ANF release. (C) 2001 Elsevier Science Inc. All rights reserved.