Histological changes underlying bupivacaine's effect on extra ocular muscle

Histological changes underlying bupivacaine's effect on extra ocular muscle

Author Hopker, Luisa Moreira Autor UNIFESP Google Scholar
Neves, Juliana de Carvalho Google Scholar
Nascimento, Daiane Jaqueline Google Scholar
Campos, Eliene Dutra Google Scholar
Mendonca, Tomas Scalamandre Autor UNIFESP Google Scholar
Zanoteli, Edmar Google Scholar
Allemann, Norma Autor UNIFESP Google Scholar
Abstract To determine the changes in the cross-sectional area (CSA) of myofibers and their subtype distribution based on the myosin isoform expression after bupivacaine (BUP) injection in the EOM of rabbits and help the understanding of strabismus correction after BUP injection in the clinical practice. A total of 32 rabbits received 0.3 mL of 1.5% BUP in the superior rectus muscle (SR) of the right eye (OD) and were sacrificed at days 7, 28, 60, and 92. Additional eight untouched rabbits were included as controls. Hematoxylin and eosin staining was performed, and ImageJ software was used to measure CSA. Immunohistochemical analysis was performed to analyze the proportion of myofibers positive for myosin types 1 (slow), 2 (fast) and embryonic. Myofiber area measurement decreased 7 days after BUP injection [SR, 1271 +/- 412 mu m(2) (control) to 909 +/- 255 mu m(2) (day 7)] after BUP injection, followed by an increasing trend after 28 days and normalization after 92 days [SR

1062 +/- 363 mu m(2) (day 28), 1492 +/- 404 mu m(2) (day 60), 1317 +/- 334 mu m(2) (day 92)]. The proportion of slow myosin-positive fibers increased in the 60-day group (88.5% +/- 16.2%). There was no statistically significant difference in fast myosin-positive fibers. The inferior rectus of both eyes showed an increase in CSA. No increase of endomysial fibrous tissue was observed after 60 and 92 days of BUP injection. Bupivacaine, when injected into the SR of rabbits, initially decreases the fiber area followed by a transient increasing trend and normalization. There is a transient increase in the proportion of slow myosin-positive fibers in the injected muscle. Muscle adaptation in untreated EOM was found with increased CSA. These findings help clarify the clinical effects of BUP in extraocular muscle.
Keywords Extraocular muscle
Bupivacaine
Strabismus
Muscle physiology
Regeneration
Slow myosin
Language English
Sponsor CNPq
Department of Ophthalmology at the Federal University of Sao Paulo
CAPES Doctorate scholarship
Date 2018
Published in Experimental Eye Research. London, v. 171, p. 62-67, 2018.
ISSN 0014-4835 (Sherpa/Romeo, impact factor)
Publisher Academic Press Ltd- Elsevier Science Ltd
Extent 62-67
Origin http://dx.doi.org/10.1016/j.exer.2018.03.004
Access rights Closed access
Type Article
Web of Science ID WOS:000433646000007
URI http://repositorio.unifesp.br/handle/11600/45980

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