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Abstract:Objective: The present study was designed to examine the involvement of bradykinin in thermal and mechanical hyperalgesia induced by chronic constriction nerve injury (CCI) using B₁ and B₂ receptor antagonists and mutant kininogen-deficient rats. Methods: Sprague-Dawley (SD) rats and Brown Norway (B/N-) rats given CCI treatment on day 0, were used as a model of neuropathic pain. Either a kinin B₁ antagonist des-Arg⁹-[Leu⁸]-bradykinin or the receptor B₂ antagonist HOE-140 was constantly infused into the left jugular vein of SD rats on days 15 to 22 after CCI. Vehicle-treated rats and sham-operated rats without nerve injury were also prepared as controls. In all rats, we observed pain behavior, and measured the latency period of paw withdrawal from the thermal stimuli and, with von Frey filaments, the mechanical pain threshold, before surgery and on days 14 and 22 after CCI. B/N-Katholiek rats, which congenitally lack plasma kininogen and release no kinin, were also tested for hyperalgesic parameters. Expression of kinin receptor mRNA in the dorsal root ganglia was detected by RT-PCR. Results: Most of the rats (88%)showed some pain behavior, which was reduced to 67% by a B₁ antagonist and to 57% by a B₂ antagonist infused between days 15 to 22. Thermal hyperalgesia was significantly reduced from 7.25 ± 0.41 sec (mean ± SEM) to 8.36 ± 0.41 sec in paw withdrawal latency on day 22 by a B₁ antagonist and from 7.24 ± 0.19 sec to 8.23 ± 0.21 sec by a B₂ antagonist (P < 0.05). Mechanical hyperalgesia was also ameliorated from 0.02 ± 0.007 g force to 0.16 ± 0.08 g force in pain threshold by a B₁ antagonist and from 0.03 ± 0.007 g force to 0.10 ± 0.003 g force on day 22 by a B₂ antagonist. Moreover, deficient B/N-Katholiek rats showed a low incidence of thermal and mechanical hyperalgesia on day 14. Expression of both B₁ and B₂ receptor mRNAs was detected in the lumbar dorsal ganglia ipsilateral to the site of the ner ve injury. Conclusion: These data suggests that kinin were at least partly involved in yielding nociceptor hypersensitivity up to day 14 after CCI. Bradykinin and its B₁ and B₂ receptors were involved in the maintenance of hyperalgesia.

The glucose transporter of human erythrocytes was reconstituted with soybean phospholipids by the freeze-thaw/sonication method and the distribution of the transporter molecules in liposomes was studied. The steady state level of glucose transport in reconstituted liposomes showed saturation when increased amounts of the transporter were used for reconstitution. The saturation curve fitted well to a theoretical curve which was derived assuming a Poisson distribution of the transporter. Freeze-fracture electron micrographs showed random distribution of intramembraneous particles on liposomes, irrespective of liposome size or amount of the transporter added. A detailed study showed a parameter of the distribution (the ratio of transporter to liposome) obtained from the transport measurement can be used for the analysis of the distribution of intramembraneous particles, indicating that most of the molecules seen as particles were active in transport.