Análise funcional e histológica da utilização da hialuronidase durante a anestesia local em nervo ciático de ratos / Functional and histological analysis of hyaluronidase use during local anesthesia of the rat sciatic nerve

AUTOR(ES)

Anna Carolina Ratto Tempestini Horliana

DATA DE PUBLICAÇÃO

2008

RESUMO

The concomitant use of the enzyme hyaluronidase (H) and local anesthetics (LA) is widely employed in ophthalmology in order to improve the effectiveness of anesthesia; in dentistry, however, this association did not seem advantageous. A new protocol was tested with the aim of drawing out local anesthesia without supplementary anesthesia. This possibility is especially interesting for patients with restriction of maximum recommended dose of LA or vasoconstrictor due to pathological conditions (e.g. heart disease). We used 2% lidocaine hydrochloride with epinephrine for sensitive, motor and proprioceptive blockade of the sciatic nerve in rats (Truant, 1958). Hyaluronidase 75 UTR was injected 30 minutes after the beginning of the anesthesia (before the recovery of the sensory function), using the contralateral limb as control (injection of LA plus the H vehicle solvent). The duration of the sensitive blockade was evaluated through the absence of the paw withdrawal reflex, using an analgesymeter. The motor blockade was evaluated by the duration of claudication (complete absence of extensor postural thrust) and by the absence of the paw stretching reflex, while the proprioceptive blockade was evaluated by the absence of hopping and tactile placing response (Thalhammer et al., 1995). Histological changes induced by H were analyzed 1h, 24h, 48h, and 72 h after the injection in the following groups: (1) Sham; (2) LA + H; (3) LA + H solvent (solv) and (4) Solv + Solv. We concluded that H draws out local anesthesia when injected before the recovery of the sciatic nerve blockade in the rat. In all groups studied, with the exception of the Sham, there was an inflammatory reaction after the injections. Inflammation was more intense after H injection, showing signs of regression after 72 hours. It is possible that the mechanism of action of H involves disorganization of the connective tissue, thus facilitating the diffusion of the residual anesthetic solution to the nerve.

ASSUNTO(S)

sciatic nerve anestésicos locais hyaluronoglicosaminidase morphology reparo tecidual morfologia nervo ciático acido hialurônico tissue repair hialuronogluconaminidase hyaluronic acid local anesthetic

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