PubMed · 13353579
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R BAUMGART. 1956-06-09. [Experience with basinarcon].. https://pubmed.ncbi.nlm.nih.gov/13353579/
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Changes in the number of receptors on the cell surface lead to modulations of physiological functions and pharmacological responses of neurons. Recent studies show that delta-opioid peptide (DOP) and mu-opioid peptide (MOP) receptors have distinct subcellular localizations in neurons. In nociceptive small neurons in the dorsal root ganglia, DOP receptors are sorted into neuropeptide-containing secretory vesicles, enabling the stimulus-induced cell surface expression of these receptors. MOP receptors are constitutively expressed on the cell surface. The physical interaction between DOP receptors and MOP receptors seems to be an important mechanism for the modulation of receptor functions. Experiments in animals show that MOP-receptor-mediated spinal analgesia is enhanced and morphine tolerance does not develop when DOP receptor functions are pharmacologically or genetically attenuated. Thus, the delivery and trafficking of DOP receptors are crucial processes that modulate opioid analgesia and tolerance.
Systemic administration of morphine induced a hyperalgesic response in the hot plate test, at an extremely low dose (1-10 microg/kg). We have examined in vivo whether morphine, at an extremely low dose, induces acute central hypernociception following activation of the opioid receptor-mediated PLC/PKC inositol-lipid signaling pathway. The PLC inhibitor U73122 and the PKC blocker, calphostin C, dose dependently prevented the thermal hypernociception induced by morphine. This effect was also prevented by pretreatment with aODN against PLCbeta3 at 2 nmol/mouse and PKCgamma at 2-3 nmol/mouse. Low dose morphine hyperalgesia was dose dependently reversed by selective NMDA antagonist MK801 and ketamine. This study demonstrates the presence of a nociceptive PLCbeta3/PKCgamma/NMDA pathway stimulated by low concentrations of morphine, through muOR1 receptor, in mouse brain. This signaling pathway appears to play an opposing role in morphine analgesia. When mice were treated with a morphine analgesic dose (7 mg/kg), the downregulation of PLCbeta3 or PKCgamma at the same aODN doses used for the prevention of the hyperalgesic effect induced, respectively, a 46% and 67% potentiation in analgesic response. Experimental and clinical studies suggest that opioid may activate pronociceptive systems, leading to pain hypersensitivity and short-term tolerance, a phenomenon encountered in postoperative pain management by acute opioid administration. The clinical management of pain by morphine may be revisited in light of the identification of the signaling molecules of the hyperalgesic pathway.
OBJECTIVE: To describe the new procedures applied for interventional radiology leading to specific anaesthetic care and organization. DATA SOURCE: Record of references from national and international journals in Medline. STUDY SELECTION: All types of articles were selected including prospective studies, practice guidelines, reviews and case reports. DATA SYNTHESIS: During interventional radiology, anaesthesia should be adapted to the duration of the procedure, the pain induced by the radiologist, the position of the patient and its medical status. General anaesthesia would be preferred for long procedures, requiring total immobility. Locoregional anaesthesia can be proposed for some cases. Sedation associating hypnotics (propofol, midazolam, sevoflurane) and opioids (alfentanil, remifentanil) is commonly used according to different schemes, as discontinuous boluses, continuous infusion, target controlled intravenous sedation or patient controlled sedation. Monitoring of temperature and diuresis may be useful for long procedures. Haemodynamic monitoring (arterial catheter, central venous pressure) and haemostatic monitoring may be necessary for interventional neuroradiology and endovascular stenting. Radiofrequency and laser procedures are often painful, requiring the choice of adequate analgesic regimen. Hydratation associated with acetylcysteine seems to be able to prevent contrast induced nephropathy in patients with risk factors for chronic renal insufficiency. CONCLUSION: As advances in interventional radiology are obvious, general organisation as well as anaesthetic procedures should be adapted to these specific techniques.