Substance P release from knee joint afferent terminals: modulation by opioids.
Perfusate obtained from the intra-articular space of the knee (100 microliters/min) in the halothane-anesthetized cat under resting conditions shows no detectable substance P-like immunoreactivity (SP-LI: less than 2 pg/20 min). Antidromic activation by electrical stimulation of the sciatic nerve at stimulus intensities which evoke activity in A beta/A delta/C but not A beta fibers or the local administration of capsaicin (10(-4) M) into the intra-articular perfusate results in a stimulus-dependent increase in the levels of SP-LI in the perfusate. This release is diminished in a naloxone-(1 mg/kg, i.v.) reversible fashion by sufentanil, D-Ala2-D-Leu5-enkephalin, and D-Pen2-D-Pen5-enkephalin, but not by U50488H (10(-4) M) added to the intra-articular perfusate. These observations thus suggest that the peripheral stores of SP-LI in small primary afferents are subject to release by antidromic activity and this release is subject to modulation by mu/delta receptors on these peripheral terminals.
Yaksh
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Laboratory of Neurosurgical Research, Mayo Clinic, Rochester, MN 55905.
D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D002415:Cats; D004558:Electric Stimulation; D020881:Enkephalin, D-Penicillamine (2,5)-; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D004745:Enkephalins / Q000494:pharmacology; D005283:Fentanyl / Q000031:analogs & derivatives / Q000494:pharmacology; D006614:Hindlimb / Q000294:innervation; D007596:Joints / Q000378:metabolism*; D009294:Narcotics / Q000494:pharmacology*; D011759:Pyrrolidines / Q000494:pharmacology; D012016:Reference Values; D012584:Sciatic Nerve / Q000502:physiology*; D013373:Substance P / Q000378:metabolism*; D017409:Sufentanil
D004745:Enkephalins; D009294:Narcotics; D011759:Pyrrolidines; D013373:Substance P; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D020881:Enkephalin, D-Penicillamine (2,5)-; D017409:Sufentanil; D002211:Capsaicin; D005283:Fentanyl