RESUMO
The aim of this study was to characterize the sarcoplasmic-endoplasmic reticulum Ca-ATPase (SERCA) isoforms in rabbit masticatory muscles compared with those in fast-twitch muscle. It was hypothesized that combined expression of the SERCA isoforms in fast- and slow-twitch muscles accounts for lower Ca-ATPase activity. SERCA was isolated by differential centrifugation, the isoforms were determined by ELISA, and the activity of each isoform was measured using a colorimetric method. Activity was tested for significance by anova, and the distribution of isoforms was assessed using the chi-square test (P < 0.05) and correlated to SERCA activity using Spearman's rank correlation. SERCA1 was predominant (90.5%) in fast-twitch muscle, whereas a mixture of SERCA isoforms was found in masticatory muscles: 62-78% was SERCA2, 20-37% was SERCA1, and the SERCA3 content was negligible. Depressor muscles showed a significantly higher content (77.8%) of SERCA2, and elevator muscles showed a higher content (35.4%) of SERCA1. Elevator muscles showed higher expression of SERCA2a (58%), and depressor muscles showed higher expression of SERCA2b (20%). The SERCA1 content was mainly SERCA1a and significantly higher for elevator muscles (33%), whereas depressor muscles showed a higher content of SERCA1b (4%). The SERCA1 content of fast-twitch muscle was mainly SERCA1a (88.5%). It is concluded that the mixture of different SERCA isoforms, along with a substantial content of SERCA2b, in masticatory muscles would support lower Ca-ATPase activity and calcium transport.
Assuntos
Músculos da Mastigação/enzimologia , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/análise , Animais , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Isoenzimas/análise , Isoenzimas/classificação , Masculino , Músculo Masseter/enzimologia , Fibras Musculares de Contração Rápida/enzimologia , Fibras Musculares de Contração Lenta/enzimologia , Músculos do Pescoço/enzimologia , Músculos Pterigoides/enzimologia , Coelhos , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/classificação , Músculo Temporal/enzimologiaRESUMO
This study verified the effect of unilateral teeth extraction on the suprahyoid muscles in gerbils (Meriones unguiculatus). Ten adult male gerbils weighing about 50g had induced occlusal alterations by upper molar teeth extraction on the left side while the other ten animals were only subjected to surgical stress, control group. After 60 days, animals of both groups, experimental and control had the suprahyoid muscles removed and processed for histological and histochemical (adenosine triphosphatase (ATPase), nicotine adenine dinucleotide tetrazolium reductase (NADH-TR) and succinate dehydrogenase (SDH)) purposes. The fiber type area was estimated in % according to Weibel method (point-counting method) using a test-system. The myosinic ATPase pH 4.7 activity in the control group of the digastric, milohyoid and geniohyoid muscles presented a small area of type I fiber and a larger area of type IIa fibers; in the experimental group, significant contractile capacity alteration was not observed. Samples of the digastric, milohyoid and geniohyoid muscles, after SDH activity, showed a small area with high metabolic activity fibers, and a large area with intermediary and low metabolic activity fibers in the control group. The milohyoid muscle of the experimental group presented low metabolic fibers in a reduced area, in both sides, however without significant difference. In the experimental group, high metabolic fibers were observed on the left side in a reduced area in the geniohyoid muscle, but without statistical significance. Thus, the geniohyoid muscle did not change the metabolic activity after occlusal alteration. In conclusion, 60 days of unilateral malocclusion induced was able to alter the fibers oxidative activity of the suprahyoid muscles, however, it does not affect the contractile property of the fibers. The digastric muscle has adequate fibers to produce fast contraction and able to resist to fatigue in intermediate degrees, but became more fatigable after unilateral exodontia.
Assuntos
Dente Molar , Músculos do Pescoço/enzimologia , Músculos do Pescoço/ultraestrutura , Extração Dentária , Adenosina Trifosfatases/metabolismo , Animais , Gerbillinae , Histocitoquímica , Técnicas Histológicas , Masculino , NADH Tetrazólio Redutase/metabolismo , Succinato Desidrogenase/metabolismoRESUMO
Estima-se que entre 1 milhão de adultos do hemisfério ocidental, 20.000 tenham anomalias nos músculos esqueléticos como conseqüência da ingestão de álcool. Estudos revelam que nestes casos ocorre uma fraqueza progressiva afetando predominantemente os músculos da coxa, ombro e quadris, e uma artrofia das fibras do tipo II ou de contração rápida. Na literatura consultada não foi observado relato do que acontece com os músculos da mastigação, por isso este estudo foi desenvolvido com o intuito de observar se as fibras de contração rápida do músculo digástrico apresentam alterações semelhantes às que ocorrem nos músculos do tronco e membros. Para tanto, amostras dos músculos digástrico e reto do abdome foram retiradas de cinco animais de cada grupo Controle (C), Alcoolizado (A) e Isocalórico (I). As amostras foram submetidas às reações de m-ATPase (com pré-incubações ácida e alcalina) e NADH-TR, para a classificação das fibras de acordo com os resultados obtidos nestas reações em FG (fast-twitch-glycolitic, FOG (fast-oxidative-glycolitic) e SO (slow-oxidative). Os resultados mostraram uma diferença significativa, na área das fibras dos tipos FG e FOG, entre os grupos estudados no músculo digástrico e na área das fibras do tipo FG no músculo reto do abdome; uma diferença sigificativa na freqüência das fibras dos tipos FG e FOG no músculo reto do abdome. Baseando-se nestes resultados, é possivel concluir que o etanol produz uma atrofia nas fibras da contração rápida dos músculos da mastigação, semelhante à dos músculos do tronco, mas com um coeficiente de atrofia diferente...