Human vascular and cardiac endothelia express mu opiate receptor transcripts

Pharmacologic and immunologic evidence suggests that nitric oxide-coupled μ-subtype opiate receptors are expressed in human vascular endothelium. In this study, we present molecular evidence of μ opiate receptor expression. Using primers derived from the human neuronal μ1 opiate receptor, we used RT-PCR to detect expression of μ transcripts from human endothelia. Sequence analysis of the RT-PCR products revealed 100% identity with the neuronal human μ1 receptor. We further show that pretreatment of human internal thoracic artery and cardiac atrial endothelium with the proinflammatory cytokines interleukin-1-α and -β led to a significant increase in both the expression of the μ transcript and in morphine-stimulated nitric oxide release measured amperometrically. Taken together, these studies provide molecular evidence that μ-type opiate receptors are expressed in human vascular endothelia and that their expression can be upregulated by proinflammatory cytokines.