M 154,129, a putative delta antagonist, reverses endotoxic shock without altering morphine analgesia.

Studies were conducted with the putative delta opiate receptor antagonist M 154,129 to evaluate its potential for reversing circulatory shock without altering nociceptive processes. M 154,129 (30 mg/kg iv) did not alter tail flick or hot plate latencies by itself, nor did it alter the antinociceptive effects of morphine (4 mg/kg iv). Following endotoxic shock hypotension in conscious rats, M 154,129 (30 or 60 mg/kg iv) produced a rapid return of arterial pressure to pretreatment levels. These data indicate that circulatory shock may be mediated at delta opioid receptors. Moreover, delta antagonists may have therapeutic benefit in reversing shock without intensification of pain.