Assessment of serum enzymatic markers of cardiomyocytes injury in female dogs submitted to ketamine S(+), atropin and xylazine association

Effect of a background Ca2+ entry pathway mediated by TRPC1 on myocardial damage of broilers with induced ascites syndrome

Ascites syndrome (AS) in chickens is associated with profound vascular remodelling and increased pulmonary artery pressure as well as right ventricular hypertrophy. Classical transient receptor potential cation channels (TRPCs) are key regulators of cardiac hypertrophy that act via regulation of calcium influx in mammals. We investigated whether classical transient receptor potential channels in chickens with right ventricular hypertrophy still possess this mechanism for regulating Ca²⁺ flux. Intravenous injection of cellulose particles was successfully used to induce AS in chickens, and tissues were examined 22 days after treatment. The chickens in the test group showed cardiac hypertrophy with oedema of the cardiac muscle and disruption of myofilaments. The right-to-total ventricle weight ratio (RV/TV), the levels of serum aspartate aminotransferase (AST) and creatine kinase (CK) of the test group were significantly higher than in the control group. Intracellular calcium levels were significantly increased in cardiomyocytes from chickens in the test group. Gene expression of TRPC3, TRPC4, TRPC5, TRPC6 and TRPC7 in heart tissues from the test group showed no significant differences compared with controls. However, TRPC1 protein levels, as well as mRNA levels, were down-regulated in the heart muscle of AS chickens (P < 0.05). Although we observed an increase in calcium concentration, the expression of TRPC1 decreased in cardiac cells. We hypothesized that an increase in intracellular free calcium concentration could inversely regulate calcium channel expression. RESEARCH HIGHLIGHTS Intracellular Ca²⁺ levels were increased in the myocardium of AS broilers. Expression of TRPC1, which mediates calcium influx, was decreased in the myocardium of AS broilers. The relationship between intracellular Ca²⁺ levels and expression of TRPC1 requires further study.

Effects of heated hydrotherapy on muscle HSP70 and glucose metabolism in old and young vervet monkeys

Increasing heat shock protein 70 (HSP70) in aged and/or insulin-resistant animal models confers benefits to healthspan and lifespan. Heat application to increase core temperature induces HSPs in metabolically important tissues, and preliminary human and animal data suggest that heated hydrotherapy is an effective method to achieve increased HSPs. However, safety concerns exist, particularly in geriatric medicine where organ and cardiovascular disease commonly will preexist. We evaluated young vervet monkeys compared to old, insulin-resistant vervet monkeys (Chlorocebus aethiops sabaeus) in their core temperatures, glucose tolerance, muscle HSP70 level, and selected safety biomarkers after 10 sessions of hot water immersions administered twice weekly. Hot water immersion robustly induced the heat shock response in muscles. We observed that heat-treated old and young monkeys have significantly higher muscle HSP70 than control monkeys and treatment was without significant adverse effects on organ or cardiovascular health. Heat therapy improved pancreatic responses to glucose challenge and tended to normalize glucose excursions. A trend for worsened blood pressure and glucose values in the control monkeys and improved values in heat-treated monkeys were seen to support further investigation into the safety and efficacy of this intervention for metabolic syndrome or diabetes in young or old persons unable to exercise.

Cardiac Dysregulation and Myocardial Injury in a 6-Hydroxydopamine-Induced Rat Model of Sympathetic Denervation

BACKGROUND

Cardiac sympathetic denervation is found in various cardiac pathologies; however, its relationship with myocardial injury has not been thoroughly investigated.

METHODS

Twenty-four rats were assigned to the normal control group (NC), sympathectomy control group (SC), and a sympathectomy plus mecobalamin group (SM). Sympathectomy was induced by injection of 6-OHDA, after which, the destruction and distribution of sympathetic and vagal nerve in the left ventricle (LV) myocardial tissue were determined by immunofluorescence and ELISA. Heart rate variability (HRV), ECG and echocardiography, and assays for myocardial enzymes in serum before and after sympathectomy were examined. Morphologic changes in the LV by HE staining and transmission electron microscope were used to estimate levels of myocardial injury and concentrations of inflammatory cytokines were used to reflect the inflammatory reaction.

RESULTS

Injection of 6-OHDA decreased NE (933.1 ± 179 ng/L for SC vs. 3418.1± 443.6 ng/L for NC, P < 0.01) and increased NGF (479.4± 56.5 ng/mL for SC vs. 315.85 ± 28.6 ng/mL for NC, P < 0.01) concentrations. TH expression was reduced, while ChAT expression showed no change. Sympathectomy caused decreased HRV and abnormal ECG and echocardiography results, and histopathologic examinations showed myocardial injury and increased collagen deposition as well as inflammatory cell infiltration in the cardiac tissue of rats in the SC and SM groups. However, all pathologic changes in the SM group were less severe compared to those in the SC group.

CONCLUSIONS

Chemical sympathectomy with administration of 6-OHDA caused dysregulation of the cardiac autonomic nervous system and myocardial injuries. Mecobalamin alleviated inflammatory and myocardial damage by protecting myocardial sympathetic nerves.

Cerebral hemorrhage increases plasma concentrations of noradrenalin and creatine kinase MB fraction with induction of cardiomyocyte damage in rats

The incidence of cardiac damage is high during acute cerebral hemorrhage. The animal data on the relationship between cerebral apoplexy and cardiac damage are lacking. Thus, the aim of the study was to evaluate the effects of cerebral hemorrhage on plasma concentrations of monoamine transmitter noradrenalin (NA), creatine kinase muscle and brain (CK-MB) isoenzyme fraction, and cardiomyocyte changes in the rat model. In this study, 140 Wistar rats were randomly and equally divided into experimental and control groups, and collagenase was injected into the right caudate nucleus to induce cerebral hemorrhage in the experimental group. Plasma NA was analyzed using high-performance liquid chromatography with electrochemical detection and serum CK-MB was measured by enzyme reaction rate method. We found that both NA and CK-MB were elevated (p < 0.05) at 6 h after cerebral hematoma formation; the levels were 2.46 ± 0.05 μg/L and 3.51 ± 0.23 μkat/L, respectively. NA and CK-MB concentrations reached peak levels at 24 h which were found to be 3.52 ± 0.06 μg/L and 5.47 ± 0.49 μkat/L, respectively. Thereafter, NA and CK-MB concentrations decreased gradually. Plasma NA declined to the preoperative level (1.66 ± 0.03 μg/L) at 72 h, while CK-MB level (2.71 ± 0.17 μkat/L) was found to be still higher than its preoperative level. It was, therefore, concluded that plasma NA might be involved in the induction and development of cardiomyocytes damage during cerebral hemorrhage.

Combination of ketamine and xylazine exacerbates cardiac dysfunction in severely scalded rats during the shock stage

Cardiac inhibition due to burn injury and anesthetics have been documented previously. However, little is known about their combined effects on cardiac function. The aim of the present study was to observe the effects of a ketamine/xylazine (K/X) combination on the cardiac function of rats with severe scalds and compare them with those of avertin. Adult rats were randomly distributed into four groups: the KXB group (scalds anesthetized with K/X, n=10), the KXC group (sham scalds anesthetized with K/X, n=10), the AVB group (scalds anesthetized with avertin, n=10) and the AVC group (sham scalds anesthetized with avertin, n=10). Ketamine and xylazine were administered at 25 and 6 mg/kg, respectively, and avertin at 200 mg/kg before full-thickness scalds or sham scalds of 30% total body surface area (TBSA) were produced. Echocardiographic parameters were assessed following injury. The heart rate (HR) in the KXB group was fatally low during the study period. Fractional shortening (FS%) and ejection fraction (EF) in the KXB group were extremely low initially and remained low. The left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) were reduced in the burned rats. Serum levels of cardiac troponin I (cTnI) were significantly higher in the KXB group than in the AVB group (1.66±0.28 vs. 1.16±0.34 ng/ml, P<0.01). The highest lung wet/dry weight ratio was observed in the KXB group. However, no evident heart tissue pathological changes were observed in these groups. The apoptotic index of myocardial cells and caspase 3 expression level were highest in the KXB group (P<0.01). In conclusion, K/X exacerbated cardiac inhibition in severely scalded rats during the shock stage by a mechanism which may involve mitochondrial apoptosis.

Tei index (myocardial performance index) and cardiac biomarkers in dogs with parvoviral enteritis

Tei index (myocardial performance) and cardiac biomarkers were evaluated in dogs with parvoviral enteritis (PVE). Tei index was calculated as isovolumic contraction time plus isovolumic relaxation time divided by ejection time. Myocardial and skeletal muscle damages were assessed by serum levels of cardiac troponin I (cTnI), creatine (phospho) kinase, lactate dehydrogenase and aspartate aminotransferase. Serum magnesium level was also determined. According to treatment response, dogs were divided into the survivor (n=20) and non-survivor groups (n=23). Seven healthy dogs served as controls. The mean value of the Tei index was higher in non-survivors, compared with survivors (p<0.02) and healthy controls (p<0.01). Serum level of cTnI in non-survivors was higher than that of survivors and controls (p<0.05). Tei index showed the highest sensitivity and specificity to predict mortality. The findings of an elevated Tei index and an increase in serum cTnI are factors associated with a poor prognosis in cases of canine parvovirosis.