Serum dosage of CPK-MB in dogs with ST deviation by chemiluminescence

摘要

: Although frequently in humans, hypoxic and ischemic heart diseases are poorly documented in dogs, with only few reports of acute myocardial infarction (AMI) in this species. Some electrocardiographic findings might suggest myocardium hypoxia/ischemia, like ST segment elevation or depression, but there are no studies showing whether deviations in ST segment are associated to myocardial injury and serum increase of creatine phosphokinase (CPK-MB). In order to investigate possible myocardial cells injury in poor perfusion conditions, 38 dogs were studied, 20 with normal electrocardiogram and 18 with ST segment elevation or depression, recorded in lead II, at a paper speed of 50 mm/sec and N sensibility (1mV=1cm). Serum measurement of creatine phosphokinase isoenzyme MB (CPK-MB) in normal dogs (group 1) determined control values (in ng/mL), which were compared to those obtained from dogs with deviation (group 2), which allowed confirmation or not of myocardial injury. CPK-MB mean values obtained from dogs in groups 1 and 2 were 0.540ng/ml (SD?±0.890)ng/mL and 0.440ng/mL (SD?±1.106), respectively. At a significance level of 5%, the relation of CPK-MB with age, mass and total creatine phosphokinase (CPK-T) was not significant in groups 1 and 2. CPK-MB showed no difference, at 5% level, between groups 1 and 2. In conclusion, it is possible to use the human chemiluminescent immunometric assay kit in canine species and that hypoxia/ischemia revealed by ST segment deviation does not mean significant myocardium injury. Index Terms:??Creatinephosphokinase; CPK-MB; dogs; ST segment Resumo: Embora frequente em humanos, as doen?§as hip?3xicas e isqu?amicas do cora?§?￡o s?￡o pouco relatadas em c?￡es, com poucos relatos de infarto agudo do mioc??rdio (IAM) nesta esp??cie. Alguns achados no eletrocardiograma podem sugerir hip?3xia/isquemia mioc??rdica, como a eleva?§?￡o ou depress?￡o do segmento ST, mas n?￡o h?? estudos que mostram se os desvios do segmento ST est?￡o associados a les?μes mioc??rdicas e aumento s??rico da creatinafosfoquinase (CPK-MB). A fim de investigar poss?-veis les?μes nas c??lulas mioc??rdicas em condi?§?μes de m?? perfus?￡o, 38 c?￡es foram estudados, 20 com eletrocardiograma normal e 18 com eleva?§?￡o ou depress?￡o do segmento ST, registrados em papel, na deriva?§?￡o II, velocidade de 50 mm/s e sensibilidade N (1mV = 1cm). A mensura?§?￡o da creatinafosfoquinase isoenzima MB (CPK-MB) em c?￡es normais (grupo 1) determinou os valores controle (em ng/ml), que foram comparados com os obtidos a partir de c?￡es com desvio (grupo 2), permitindo a confirma?§?￡o ou n?￡o da les?￡o mioc??rdica. Os valores m??dios de CPK-MB obtidos de c?￡es nos grupos 1 e 2 foram 0,540ng/ml (DP?±0,890) e 0,440ng / ml (DP ?± 1.106), respectivamente. A um n?-vel de signific?￠ncia de 5%, a rela?§?￡o de CPK-MB com a idade, massa e creatinofosfoquinase total (CPK-T) n?￡o foi significativa nos grupos 1 e 2. N?￡o houve diferen?§as na CPK-MB, ao n?-vel de 5%, entre os grupos 1 e 2. Conclui-se que ?? poss?-vel utilizar o kit de ensaio imunom??trico por quimioluminesc?ancia humano na esp??cie canina e que a hipoxia/isquemia revelada pelos desvios do segmento ST, n?￡o significa les?￡o mioc??rdica. Termos de Indexa?§?￡o:??Creatinafosfoquinase; CPK-MB; c?￡es; segmento ST Introduction Acute myocardial infarction is a common affection in humans, having as a typical symptom the "chest pain" irradiating to the back and arms. Individuals with these symptoms are monitored by electrocardiogram and by dosing myocardial hypoxia-ischemia markers (Bonow et al. 2009, Tharwat 2013). Myocardial hypoxia is the insufficient cardiac muscle oxygenation (Robbins et al. 2001), in spite of the adequate perfusion (Bonow et al. 2009), while ischemia is the oxygen deprivation followed by inadequate metabolites removal. During hypoxia, enzymes are liberated in the blood circulation (Loegering & Critz 1971) and, in case of hypoxia/myocardial infarction, creatine phosphokinase (CPK) catalyses the reversible reaction: creatine + ATP phosphocreatine + ADP, named Lohman Reaction (Aktas et al. 1993, Bottomley & Weiss 2001). CPK is a dimeric molecule of 381 amino acids that consists of two subunits, (M and B, which have the same weight but are immunologically distinct and synthesized by two different genes) and presents 282 cysteine residues that are necessary for its catalytic activity. There are three isoenzymes: CPK-MM, present in striated muscle; CPK-BB, present predominantly in the brain and digestive system and CPK-MB, present in the cardiac tissue, kidneys, intestines and lungs (Aktas et al. 1993). CPK synthesis control is not well understood. Studies show that, in dogs myocardium, short term anoxia causes an increase in the concentration of the mRNA for the B subunit synthesis, resulting in an increase of 35% to 100% of the CPK-MB serum activity, therefore it is used for the diagnosis of experimentally induced acute myocardial infarction in dogs (Aktas