Human vascular and cardiac endothelia express mu opiate receptor transcripts

Pharmacologic and immunologic evidence suggests that nitric oxide-coupled m u-subtype opiate receptors are expressed in human vascular endothelium. In this study, we present molecular evidence of mu opiate receptor expression. Using primers derived from the human neuronal mu l opiate receptor, we use d RT-PCR to detect expression of mu transcripts from human endothelia. Sequ ence analysis of the RT-PCR products revealed 100% identity with the neuron al human mu l receptor. We further show that pretreatment of human internal thoracic artery and cardiac atrial endothelium with the proinflammatory cy tokines interleukin-1-alpha and -beta led to a significant increase in both the expression of the mu transcript and in morphine-stimulated nitric oxid e release measured amperometrically. Taken together, these studies provide molecular evidence that mu-type opiate receptors are expressed in human vas cular endothelia and that their expression can be upregulated by proinflamm atory cytokines.