Cerebrospinal fluid concentrations of substance P and (met)enkephalin-Arg6-Phe7 during surgery and patient-controlled analgesia.
The possible role of two neuropeptides (substance P and (Met)enkephalin-Arg6-Phe7) in nociception were studied in 14 surgical patients. Lumbar cerebrospinal fluid (CSF) concentrations of the putative excitatory afferent transmitter substance P and the mu and delta receptor agonist (Met)enkephalin-Arg6-Phe7 were measured during general anesthesia for abdominal surgery and during the postoperative period when patient-controlled analgesia (PCA) was used for control of pain. The CSF was sampled through an intrathecal catheter. Seven of the patients were randomly assigned to receive neurolept anesthesia; the rest were given isoflurane anesthesia without narcotics. No statistically significant changes occurred in substance P concentrations in CSF during surgery or postoperative PCA, nor were there significant differences between the two groups. There was, however, a significant correlation between CSF substance P concentrations before the start of PCA and pain assessment on a visual analogue scale. The individual changes in substance P concentrations during PCA was also inversely correlated to the consumption of meperidine. The CSF (Met)enkephalin-Arg6-Phe7 concentrations were below the level of detection in seven of the patients before anesthesia. A large interindividual variability in both substance P and (Met)enkephalin-Arg6-Phe7 concentrations was evident. The absence of major changes in CSF neuropeptide concentrations was unexpected. Apparently inter-individual variations in neuropeptide output are considerable.
Sjöström
S
S
Department of Anesthesiology, University Hospital, Uppsala, Sweden.
Tamsen
A
A
Hartvig
P
P
Folkesson
R
R
Terenius
L
L
D000328:Adult; D000768:Anesthesia, General; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000134:cerebrospinal fluid; D005260:Female; D006801:Humans; D008297:Male; D010149:Postoperative Pain / Q000134:cerebrospinal fluid / Q000517:prevention & control; D013373:Substance P / Q000134:cerebrospinal fluid* / Q000502:physiology; D013514:Surgical Procedures, Operative; D013997:Time Factors
D013373:Substance P; D004744:Enkephalin, Methionine; C028719:enkephalin-Met, Arg(6)-