Capsaicin-induced vasoconstriction in the mouse knee joint: a study using TRPV1 knockout mice.
Capsaicin is the pungent component of chilli peppers that concomitantly activates and desensitizes C-fibre and Adelta sensory nerve fibres. Stimulation causes an acute neurogenic response including vasodilation, plasma extravasation and hypersensitivity. However, in the present study we have shown that capsaicin produces a dose-dependent vasoconstrictor effect in the mouse knee joint via Transient Receptor Potential Vanilloid 1 (TRPV1) receptor activation. A (125)I-albumin accumulation technique showed that the intravascular volume of capsaicin-treated joints in wild type (WT) mice was significantly reduced compared to TRPV1 knockout mice (p<0.01). Similarly, a laser Doppler technique showed significantly reduced blood flow in the capsaicin-treated joints of WT compared to TRPV1 knockout mice (p<0.001). Pretreatment with guanethinidine (50 mg kg(-1), i.p.) had no effect on the vasoconstriction. These data are important considering the involvement of TRPV1 receptors in joint disease. The mechanisms underlying the vasoconstriction therefore require further investigation.
Keeble
Julie Elizabeth
JE
Cardiovascular Division, New Hunt's House, King's College London, Guy's Campus, SE1 1UL, UK. julie.keeble@kcl.ac.uk
Brain
Susan Diana
SD
D000418:Albumins / Q000378:metabolism; D000818:Animals; D001168:Arthritis / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D001808:Blood Vessels / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology; D002211:Capsaicin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D018836:Inflammation Mediators / Q000494:pharmacology; D007719:Knee Joint / Q000098:blood supply* / Q000187:drug effects / Q000294:innervation*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009619:Nociceptors / Q000187:drug effects / Q000378:metabolism; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000502:physiology*; D017779:Sympathetic Fibers, Postganglionic / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D050916:TRPV Cation Channels / Q000235:genetics*; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*
D000418:Albumins; D018836:Inflammation Mediators; D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; D002211:Capsaicin