Changes in the blood redox status of horses subjected to combat training

Combat training of police horses, involving physical activity in the presence of environmental stressors, poses a risk of oxidative stress. This study compared the oxidative imbalance after combat training in horses in the regular police service and in horses that had just been schooled. Blood collection was performed immediately after training and after 16 h rest. The activity of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT), and total antioxidant status (TAS) were determined as the markers of enzymatic antioxidant defence. At the same time, lipid peroxidation (TBARS) and protein carbonylation (Carb) were assessed as oxidation biomarkers. Additionally, oxidative imbalance indexes such as SOD/CAT, SOD/GPx, TBARS/TAS and TBARS/GPx were calculated. Animals during schooling had significantly lower SOD activity in erythrocytes than those experienced. CAT activity in erythrocytes was insignificantly higher immediately after training than during recovery. The SOD/GPx ratio was higher in experienced animals, which may reflect the intra-erythrocyte imbalance between enzymes producing and degrading hydrogen peroxide towards the first one. The concentration of carbonyl groups was significantly higher after the combat training compared to the recovery period in all horses. In inexperienced animals slight increase in TBARS/TAS and TBARS/GPx indexes were observed during the recovery time after exercises, contrary to experienced horses, in which these markers decreased slightly. These results suggest that the oxidative imbalance in inexperienced horses, although less pronounced just after combat training, was more prolonged as compared to horses in regular service.

Effects of non- aureus staphylococci on colostrum composition, properties and fatty acid profile in cow - a preliminary study

By providing the body with essential nutrients, colostrum plays an immune and immunostimulating function. Colostrum quality depends on multiple factors, including microbial presence. This study aimed to explore the effect of non-aureus staphylococci on colostrum quality. Physical and chemical properties, fatty acid profile of cow colostrum were determined. In our study, we identified three non- aureus staphylococci species in the colostrum: S. sciuri, S. xylosus and S. warneri. The percentage of dry matter in staphylococci positive and negative colostrum samples did not differ significantly. Contents of fat, protein, and lactose in the colostrum were similar. The content of butyric (С4:0) and capric (С10:0) acids was significantly higher in the colostrum fat from samples positive for non- aureus staphylococci. Total bacterial count was lower in non- aureus staphylococci positive samples, while pH increased. The percentage of β-casein was lower in colostrum with a positive culture for non- aureus staphylococci.

Evaluation of selected hematological, biochemical and oxidative stress parameters in stored canine CPDA-1 whole blood

Blood transfusions are mainly given to intensive care patients; therefore, additional complications that could arise from storage lesions in preserved blood should be avoided. It has been shown that human stored red blood cells are subject to changes that are considered to be a number of interdependent processes involving metabolic disarrangement and oxidative stress. The aim of our study was to determine alterations in selected hematological and biochemical parameters and to assess whether and when oxidative stress is a significant phenomenon in stored dog CPDA-1 whole blood. Ten ½ unit bags of whole blood donated from dogs and preserved with CPDA-1 (anticoagulant containing citrate, phosphate, dextrose and adenine) were stored for 5 weeks. Each week, a 9 ml sample was drawn aseptically to measure hematological parameters, selected metabolites, free hemoglobin content, osmotic fragility, antioxidant enzyme activity, total antioxidant capacity, malondialdehyde concentration and protein carbonyl content.

The results revealed an MCV decrease in the first week of storage and then a gradual increase; osmotic fragility decreased at that time and remained low throughout the study period. Leukodepletion became significant in the fourth week of storage. The free hemoglobin concentration continuously increased, with the greatest changes observed in the last two weeks of storage. The total antioxidant capacity changed in a reverse manner. Superoxide dismutase and glutathione peroxidase activities decreased from week 0 to week 3, and catalase activity tended to decrease over time. The highest malondialdehyde concentrations in blood supernatant were measured in the first week of storage, and the carbonyl concentration increased after 35 days.

Hematological changes and oxidative stress are already present in the first week of storage, resulting in depletion of the antioxidant system and subsequent accumulation of oxidation products as well as erythrocyte hemolysis, which are most pronounced at the end of the storage period.

Comparison of effect of parenteral and oral supplementation of Selenium and vitamin E on selected antioxidant parameters and udder health of dairy cows

The aim of this study was to compare the effect of parenteral and oral supplementation of Selenium (Se) and vitamin E (VTE) on selected antioxidant parameters in blood and colostrum as well as their effect on the incidence of mastitis in dairy cows during the final phase of gravidity (6 weeks) and first two weeks after calving. For the practical part of the study 36 dairy cows of Slovak pied breed in the second to fourth lactation-gestation cycle were selected. The animals weredivided into three groups: the control (C) and two experimental groups (D1 and D2). The selected groups were treated as follows: in group D1 products containing Se (Selevit inj.) and vitamin E (Erevit sol. inj.) were administered intramuscularly twice, six and three weeks prior to parturition; in group D2 a vitamin-minerals supplement in the form of sodium selenite (Na2SeO3) and dl-α-tocopherol acetate were supplemented orally for six weeks calving. The blood samples were collected from the vena jugularis in dairy cows approximately 42 days before calving (control sampling), on parturition day, and the 14th day after calving. Higher concentrations of Se and VTE were found in the blood plasma samples of both experimental groups collected on the day of parturition. In addition, the orally supplemented group (D2) showed higher Se and α-tocopherol concentrations in blood plasma on the14th day after calving as well a reduction of occurrence of mastitis by about 25 % compared to the control group. The relationship between inflammatory response and oxidative stress was also confirmed. The concentrations of milk malondialdehyde indicating lipid peroxidation during mastitis were significantly higher in milk samples from infected cows than in milk samples from healthy animals in each monitored group. In order to prevent oxidative stress and moderate inflammatory response in dairy cows it is very important to optimally balance their nutritive needs with an appropriate ratio of Se and VTE supplements. Therefore we still recommend supplementation of the cows' postpartum dietwith 0.5 mg of Se/kg dry matter (DM) and 102 mg of dl-α-tocopherol acetate/kg DM to stabilize their optimal blood levels, stimulate the activity of glutathione peroxidase and reduce the incidence of mastitis.

Local Effects of a 1940 nm Thulium-Doped Fiber Laser and a 1470 nm Diode Laser on the Pulmonary Parenchyma: An Experimental Study in a Pig Model

The lungs are a common site of metastases from malignant tumors. Their removal with a minimal but safe tissue margin is essential for the long-term survival of patients. The aim of this study was to evaluate the usefulness of a 1940 nm thulium-doped fiber laser (TDFL) and a 1470 nm diode laser (DL) in a pig model of lung surgery that involved the incision and excision of lung tissue. Histopathological analysis was performed on days 0 and 7 after surgery. Neither TDFL nor DL caused significant perioperative or postoperative bleeding. Histological analysis revealed the presence of carbonized necrotic tissue, mixed fibrin-cellular exudate in the superficial zone of thermal damage and bands of deeper thermal changes. The mean total width of thermal damage on day 0 was 499.46 ± 61.44 and 937.39 ± 109.65 µm for TDFL and DL, respectively. On day 7, cell activation and repair processes were visible. The total width of thermal damage was 2615.74 ± 487.17 µm for TDFL vs. 6500.34 ±1118.02 µm for DL. The superficial zone of thermal damage was narrower for TDFL on both days 0 and 7. The results confirm the effectiveness of both types of laser in cutting and providing hemostasis in the lungs. TDFL caused less thermal damage to the lung parenchyma than DL.

Atherosclerosis Development and Aortic Contractility in Hypercholesterolemic Rabbits Supplemented with Two Different Flaxseed Varieties

Alpha-linolenic acid (ALA) is widely regarded as the main beneficial component of flax for the prevention of cardiovascular disease. We evaluated the effect of the transgenic flaxseed W86-which is rich in ALA-on the lipid profile, atherosclerosis progression, and vascular reactivity in hypercholesterolemic rabbits compared to the parental cultivar Linola with a very low ALA content. Rabbits were fed a basal diet (control) or a basal diet supplemented with 1% cholesterol, 1% cholesterol and 10% flaxseed W86, or 1% cholesterol and 10% Linola flaxseed. A high-cholesterol diet resulted in an elevated plasma cholesterol and triglyceride levels compared to the control animals. Aortic sections from rabbits fed Linola had lower deposits of foamy cells than those from rabbits fed W86. A potassium-induced and phenylephrine-induced contractile response was enhanced by a high-cholesterol diet and not influenced by the W86 or Linola flaxseed. Pretreatment of the aortic rings with nitro-L-arginine methyl ester resulted in a concentration-dependent tendency to increase the reaction amplitude in the control and high-cholesterol diet groups but not the flaxseed groups. Linola flaxseed with a low ALA content more effectively reduced the atherosclerosis progression compared with the W86 flaxseed with a high concentration of stable ALA. Aorta contractility studies suggested that flaxseed ameliorated an increased contractility in hypercholesterolemia but had little or no impact on NO synthesis in the vascular wall.

Maintaining Optimal Mammary Gland Health and Prevention of Mastitis

In dairy industry, quality of produced milk must be more important than quantity without a high somatic cells count (SCC) or pathogens causing mastitis of dairy cows and consumer diseases. Preserving the good health of dairy cows is a daily challenge for all involved in primary milk production. Despite the increasing level of technological support and veterinary measures, inflammation of the mammary gland–mastitis, is still one of the main health problems and reasons for economic losses faced by cow farmers. The mammary gland of high-yielding dairy cows requires making the right decisions and enforcing the proper measures aimed at minimizing external and internal factors that increase the risk of intramammary infection. Due to the polyfactorial nature of mastitis related to its reduction, the effectiveness of commonly used antimastitis methods tends to be limited and therefore it is necessary to find the areas of risk in udder health programs and monitoring systems. Only by implementing of complete udder health programs should be accompanied by research efforts to further development these complete udder health control. The present review analyses the current knowledge dealing with damping and prevention of mastitis include SCC control, proper nutrition, housing and management, milking and drying as practiced in dairy farming conditions. This information may help to improve the health of the mammary gland and the welfare of the dairy cows as well as the production of safe milk for consumers.

Impact of humic acid as an organic additive on the milk parameters and occurrence of mastitis in dairy cows

Given growing concerns about the use of antibiotics in the treatment of animals, identifying organic alternatives as feed additives to improve animal health and the development of immune responses has become of interest in dairy farming. Humic acids (HA) seem to be a suitable alternative with a favorable impact on the health and production parameters of animals. This study aimed to determine the effects of an HA supplemented diet on milk parameters as well as the effects on somatic cell count (SCC) and the occurrence of mastitis in dairy cows during the peripartum period. Twenty dairy cows in the last stage of pregnancy were selected from a herd of 140 cows. The selected cows were randomly divided into two groups: control (C) and experimental (E). The two groups were fed the same feed mixture and group E was additionally supplemented with HA at a total dose of 100 g per cow per day during the last 50 days of pregnancy. The milk parameters (dry matter, lactose, fat, crude protein, casein and milk urea) and SCC of every cow, and the presence of mastitis, were checked on days 10 and 30 during the first month of lactation. The results of the study show that dietary supplementation with HA significantly reduced the milk urea (MU) content and SCC on the 10th day after calving but did not affect the other milk compositions. In addition to the decreased MU and SCC, the number of positive quarters detected by the California Mastitis Test was reduced by 20.0% and the occurrence of mastitis caused by coagulase-negative staphylococci (CNS). Based on the obtained results we can conclude that the addition of HA stabilizes the nutrient digestion, as was confirmed by a reduced MU content in the supplemented group. Their indirect beneficial effects improved the development of immune responses, resulting in decreased SCC and the occurrence of mastitis caused by CNS.

Fatty acid profile of ewe's milk infected with Staphylococcus spp

BACKGROUND

Mastitis in sheep caused by Staphylococcus spp. is a serious concern for dairy farming.

AIMS

The objective of this study was to evaluate the impact of the intramammary infection (IMI) caused by Staphylococcus spp. on the lon g-chain fatty acid profile and composition of ewe's milk.

METHODS

The experiment was conducted in a herd of Zoslachtena Valaska sheep. Half-udder milk samples were collected from 20 weight-matched sheep at the peak of their first or second lactation. The basic physicochemical composition of milk, somatic cell count (SCC), Staphylococcus spp. infection, and total bacterial contamination (TBC) were determined. The fatty acid profile of the milk fat was determined using gas chromatography.

RESULTS

The SCC in milk infected with Staphylococcus spp. was 3.25 times higher (P<0.01) than that in the uninfected milk samples. The content of lauric acid (С12:0) was higher (P<0.05) in the milk fat of infected ewes. A significant increase (P<0.05) in the share of linoleic acid (C18:2n6t), arachidonic acid (C20:4n6), and a decrease (P<0.01) in the vaccenic acid (C18:1n7t) were observed in the milk collected from ewes infected with Staphylococcus spp.. Staphylococcus spp. infection increased the ratio of n-6 to n-3 polyunsaturated fatty acids.

CONCLUSION

Changes in the fatty acid profile of milk caused by Staphylococcus spp. infection decrease the value of ewes' milk as a health-promoting product.

Aging Markers in Equine Red Blood Cells

Detection of hematopoietic activity in horses is a challenge due to the lack of cells carrying reticulocyte markers such as RNA remnants or CD71 in the circulation. In this study, we fractionated equine red cells according to their density and analyzed the cells forming low (L), medium (M), and high (H) density fractions for markers of aging such as membrane loss, oxidation, and alterations in the intracellular free Ca²⁺ levels. Cells forming L and M fraction were highly heterogeneous in projected areas and shapes, and had higher propensity to swell in response to hypo-osmotic challenge than the cells from the H fraction. The densest cells were deprived of band 3 protein compared to the cells within L or M fraction. Furthermore, the equine red cells from the H fraction were hyper-oxidized compared to the cells within M and L fractions as follows from an increase in autofluorescence characteristic for oxidized damaged hemoglobin and from thiol oxidation as detected using monobromobimane. The lightest cells showed lower free thiol content compared to the red blood cells from the M fraction, but did not contain oxidized hemoglobin. Finally, the majority of red blood cells forming L, M, and H fraction prominently differed from each other in intracellular free Ca²⁺ levels and its distribution within the cells. Based on the obtained findings, we suggest that intraerythrocytic Ca²⁺ levels and its subcellular distribution, eosin-5-maleimide binding test for band 3 abundance, and autofluorescence of cells along with the changes in red blood cell indices, distribution width and creatine levels may become potential markers of regenerative erythropoiesis in horses. Validation of the power of these potential markers of red cell aging is pending.

Assessment of lipid peroxidation in dairy cows with subclinical and clinical mastitis

Mastitis is still one of the major causes of economic losses in dairy sector. The routine application of bacteriologic examination of milk samples is often insufficient and for this reason, alternative parameters are used to identify trends in the development of the udder health. Therefore, the objectives of this study were to determine the relationship of oxidative product levels, using malondialdehyde (MDA) as a marker on occurrence of mastitis and its causing pathogens. Dairy herd of 223 Slovak spotted cattle were tested for etiology and occurrence of mastitis based on assessment of clinical signs, abnormal udder secretions, Californian Mastitis Test (CMT) with subsequent collecting of milk samples for bacteriological examination. From 892 quarter milk samples were selected for MDA detection 51 subclinical (SM) and 26 clinical mastitis (CM) quarters with positive CMT score and positive bacteriological examination of Staphylococcus spp. and Streptococcus spp. as well 40 healthy quarters. Results showed that among the current pathogens of the mammary gland belong CNS, S. aureus, S. sanguinis, S. uberis and E. coli, which were the most frequently isolated from SM and CM. The highest MDA level was observed from clinical cases of mastitis however, increased MDA levels were detectable from subclinical cases. Bacterial isolates from subclinical quarter milk samples are different levels of MDA. In this study, we found that quarter milk samples infected with S. uberis were higher compared to other pathogens. In conclusion, differences in both severity of mastitis and mastitic pathogens were associated with differences of oxidative products in infected udders.

Publisher Correction: Low-level light therapy reduces platelet destruction during extracorporeal circulation

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Low-level light therapy reduces platelet destruction during extracorporeal circulation

Extracorporeal circulation causes many deleterious effects on blood cells. Low-level light therapy (LLLT) in the red/near-infrared spectral range is known for its cytoprotective properties but its use during cardiopulmonary bypass (CPB) has not yet been studied. We aimed to assess whether LLLT protects platelets during CPB. 24 pigs were connected to 1-hour-CPB and observed for the next 23 hours. In 12 animals, blood circulating through the oxygenator was treated with LLLT. Platelet count and function were monitored throughout the experiment. The decrease in platelet count was greater in the control group, especially during CPB and after 24 hours. In LLLT group CD62P expression remained quite stable up to the 12^th hour of the experiment, whereas in the control group it continuously decreased till the end of observation. Platelets in the control group were more prone to aggregation in the postoperative period than at the beginning of the experiment, whereas platelets in the LLLT group aggregated similarly or less intense. Limitation of platelet loss, pattern of aggregation and CD62P expression suggest that LLLT may stabilize platelet function during CPB and diminish the negative effects associated with the interaction of cells with an artificial surface.

Low-Level Light Therapy Protects Red Blood Cells Against Oxidative Stress and Hemolysis During Extracorporeal Circulation

Aim: An activation of non-specific inflammatory response, coagulation disorder, and blood morphotic elements damage are the main side effects of the extracorporeal circulation (ECC). Red-to-near-infrared radiation (R/NIR) is thought to be capable of stabilizing red blood cell (RBC) membrane through increasing its resistance to destructive factors. We focused on the development of a method using low-level light therapy (LLLT) in the spectral range of R/NIR which could reduce blood trauma caused by the heart-lung machine during surgery. Methods: R/NIR emitter was adjusted in terms of geometry and optics to ECC circuit. The method of extracorporeal blood photobiomodulation was tested during in vivo experiments in an animal, porcine model (1 h of ECC plus 23 h of animal observation). A total of 24 sows weighing 90-100 kg were divided into two equal groups: control one and LLLT. Blood samples were taken during the experiment to determine changes in blood morphology [RBC and white blood cell (WBC) counts, hemoglobin (Hgb)], indicators of hemolysis [plasma-free hemoglobin (PFHgb), serum bilirubin concentration, serum lactate dehydrogenase (LDH) activity], and oxidative stress markers [thiobarbituric acid reactive substances (TBARS) concentration, total antioxidant capacity (TAC)]. Results: In the control group, a rapid systemic decrease in WBC count during ECC was accompanied by a significant increase in RBC membrane lipids peroxidation, while in the LLLT group the number of WBC and TBARS concentration both remained relatively constant, indicating limitation of the inflammatory process. These results were consistent with the change in the hemolysis markers like PFHgb, LDH, and serum bilirubin concentration, which were significantly reduced in LLLT group. No differences in TAC, RBC count, and Hgb concentration were detected. Conclusion: We presented the applicability of the LLLT with R/NIR radiation to blood trauma reduction during ECC.

Sheep model of haemodialysis treatment

More than two million patients received haemodialysis (HD) in 2013. Many methods for improving dialysis therapy outcomes have been tested. Nevertheless, patients continue to experience high morbidity and mortality rates. We aimed to develop an animal model of HD treatment to study methods that would prevent the adverse effects of renal replacement therapy. The study was conducted using six male Merino sheep. The animals underwent a two-step bilateral nephrectomy, and a permanent dual-lumen catheter was inserted into the jugular vein. In each animal, 10 short, daily HD treatments were conducted. The dialysis prescription was adjusted individually to each animal. Measures of dialysis adequacy (spKt/V and urea reduction ratio [URR]) were calculated for each HD treatment. All animals remained in a good clinical state during the experiment. However, a sustained decrease in red blood cell count was detected. The average URR was 0.65 ± 0.01, whereas the calculated spKt/V was approximately 1.16 ± 0.03. Neither hyperphosphataemia nor a significant decline in serum albumin concentrations were detected during the study. A sustained increase in serum potassium concentrations was detected on consecutive days of the experiment. All sheep survived the treatment and were euthanized at the end of the experiment. In conclusion, we developed a reproducible sheep model of HD treatment. The gentle nature and specific anatomical features of sheep provided easy blood access and allowed us to perform HD without pharmacological intervention. However, some differences in sheep physiology relative to human physiology must be considered when interpreting the results of the study.

In Vitro Study of Caecal and Colon Microbial Fermentation Patterns in Wild Boar (Sus scrofa scrofa)

The aim of this study was to evaluate wild boar (Sus scrofa scrofa) caecal and colon products of microbial activity including short chain fatty acids (SCFA), ammonia and methane concentrations. The in vitro method was applied to caecal and colon contents after 12 and 24-hour incubation with the substrate (wheat bran), or without any additive (control samples). The pH was also measured in each sample. In samples incubated with the substrate, a lower pH was noted as compared to the control (P < 0.001). In terms of the total SCFA concentration, the hindgut microbial fermentation pattern of wild boar was characterized by a high acetate level, followed by propionate and then butyrate at a ratio of 7:1.5:1. Substrate addition decreased acetate molar proportions (P < 0.001) and increased those of butyrate (P < 0.001) as well as propionate (P < 0.05). The total SCFA level in fresh, unincubated caecal samples (128 mmol/kg) was similar to that in the colon (111 mmol/kg). The ammonia concentrations were at the level of 0.8-1.5 mmol/kg of hindgut content and did not differ between the two investigated hindgut parts. Methanogenesis was also similar in the caecum and colon and after 24h was 2.69 mmol/kg and 2.27 for caecal colon control samples, respectively. The substrate increased total gas production and methane concentration (P < 0.001).

Influence of ovariohysterectomy and deslorelin acetate on the spontaneous activity of the rabbit urinary bladder in vitro

Lower urinary tract symptoms are not only a serious health problem but also a substantial sociologic issue affecting human beings and companion animals. Estrogen deficiency is considered an etiologic factor of urinary incontinence in postmenopausal women and spayed female dogs. However, insufficient effectiveness of hormonal therapy has caused an intensive search for new therapeutic options. GnRH analogs have positive clinical effects in neutered female dogs suffering from incontinence, but the mechanism of action is not known. The aim of our study was to determine the effect of long-acting deslorelin acetate on the spontaneous activity of urinary bladder sections from a rabbit model of long-term estrogen deprivation. The study was conducted on 21 female New Zealand White rabbits divided into the following groups: control group, ovariohysterectomized (OHX) group, and ovariohysterectomized group given a deslorelin acetate implant. Urinary bladders were excised immediately after sacrifice, and the spontaneous activity of dorsal and ventral strips of the bladder body was examined in organ bath chambers. The amplitude and frequency of the spontaneous contractions were evaluated. Most of the sections developed spontaneous activity. Ovariohysterectomy caused a decrease in the amplitude of spontaneous contractions of the tissues obtained only from the dorsal part of the bladder body. After OHX, the frequency was higher compared with the control group in both parts of the bladder. Deslorelin acetate did not significantly affect the spontaneous contraction amplitude but caused a decrease in the frequency in the dorsal and ventral parts of the bladder. In conclusion, long-term changes in the levels of hormones and other regulatory substances associated with the reproductive system are related to altered spontaneous activity of the urinary bladder, which may impact the symptoms of urgency and incontinence appearing in women after menopause and in female animals after gonadectomy. However, long-acting deslorelin acetate partially reverses the effect of OHX on the spontaneous activity of the bladder. This process might underlie the positive effects of GnRH analogs in incontinent spayed female dogs.

β-adrenergic antagonists influence abdominal aorta contractility by mechanisms not involving β-adrenergic receptors

β-adrenergic receptors (β-AR) are widely distributed in the cardiovascular system, where they considerably contribute to the control of its functions. β-blockers are commonly used in the treatment of disorders of the circulatory system. They act primarily by inhibiting cardiac β-receptors. However, there are also reports of pleiotropic action of β-blockers as well as of new compounds created to study β3 adrenergic receptors. The study aimed to investigate additional mechanisms of action of β-AR inhibitors in the rabbit abdominal aorta with emphasis on their action on α-adrenergic receptors and calcium influx. Responses to propranolol, betaxolol, metoprolol and SR59230A were evaluated in phenylephrine and PGF(2alpha) precontracted aortic rings. The effect of propranolol on the phenylephrine concentration-contraction curve was examined. Propranolol (≥ 10 μM) and SR59230A (≥ 0.1 μM) induced relaxations in phenylephrine-precontracted rings, while betaxolol and metoprolol had little effect. The β-AR inhibitors produced further contraction of tissues preincubated with PGF(2alpha), excluding SR59230A, which after initial contraction, elicited marked relaxation at a concentration above 1 ĕM. 100 μM of propranolol caused a significant rightward shift of the concentration-contraction curve to phenylephrine with no reduction in the maximum response. Incubation of aortic rings in phentolamine reduced the maximal contraction to propranolol; verapamil pretreatment by contrast enhanced contractile response. In conclusion, SR59230A and propranolol most probably act as α1-AR competitive antagonists in the presence of phenylephrine in rabbit abdominal aortic rings. After α-ARs blockade, propranolol exerts a weak relaxing activity connected with Ca2+ channel inactivation. SR59230A at a high concentration acts on the rabbit aorta by an additional mechanism needing further investigation.

Nonspecific effects of ligands on the beta-adrenergic receptors in rabbit abdominal aorta in vitro

The study was conducted on 30 New Zealand rabbits weighing 3-4 kg from which sample strips of the abdominal aorta were collected. The study investigated the in vitro reaction of rabbit aorta smooth muscle to ligands binding to beta-adrenergic receptors. The response of aortic strips to beta-adrenergic receptor agonists (dobutamine, isoproterenol, salbutamol) and the influence of beta-adrenergic receptor antagonists (propranolol, betaxolol) on contractile activity was determined. All tested agonists induced contraction of the rabbit abdominal aorta muscle in a concentration-dependent manner (dobutamine >> isoproterenol > salbutamol). Enhanced reaction to low concentrations of agonists (dobutamine, isoproterenol) after administration of propranolol and inhibition of contractility in the presence of high concentrations thereof (dobutamine, salbutamol) was observed. Maximal reaction to agonists decreased after betaxolol pretreatment. The results indicate that all the substances with beta-agonist activity also possess contracting properties (presumably by acting at alpha-adrenergic receptors), but are much weaker in the case of isoproterenol and salbutamol than for dobutamine. Propranolol and betaxolol reduce the contractile response of smooth muscle using probably other mechanisms than those associated with adrenergic receptors.

Experimental methods of abdominal aortic aneurysm creation in swine as a large animal model

Animal models of abdominal aortic aneurysms (AAA) enable preclinical studies on new therapeutic approaches and help to understand pathophysiology of the disease. The aim of this study was to demonstrate the effectiveness of selected methods of experimental induction of abdominal aortic aneurysm in swine and to adapt the EMG examination (electromyography) to record the vessel wall changes. The animals were divided into 3 groups comprising 4 individuals in whom AAA was surgically induced. In the first group the AAA was induced by mechanical stretching of the aortic wall and injection of 500 IU elastase under pressure. The second group received elastase and 6000 IU of collagenase. In the third group 0.5 M CaCl2 solution was introduced additionally. Enlargement of abdominal aorta was monitored for 4 weeks. The first group did not show any aorta dilatation. In the second group the aortic lumen was dilated on average by 71±3.5% (P≤0.001) as shown at autopsy and by 76.6±9.3% as measured by the ultrasound method. In the third group aorta was dilatated by 104.2±11.3% as obtained by ultrasound and 72±3% at post-mortem examination. Myoelectric activity of VSMC (vascular smooth muscle cell) was demonstrated and it was characterized by the presence of three types of waves closely related to the pressure changes in the vessel lumen. We conclude that collagen fibers damage plays a significant role in the AAA development in swine. The inflammatory process in the vessel's wall also contributes to AAA development. However, myoelectrical activity of VSMC does not significantly change despite histologically confirmed loss of muscular layer.

In vitro study on the effects of some selected agonists and antagonists of alpha(1)-adrenergic receptors on the contractility of the aneurysmally-changed aortic smooth muscle in humans

The study included 18 sections of the aneurysmally-changed abdominal aortas, obtained from patients of the Provincial Specialist Hospital in Wroclaw and 18 sections of normal abdominal aortas obtained from swine. The collected samples were placed horizontally in the incubation chamber. Changes in their transverse section area were registered. They were stretched to a tension of 5 mN. Krebs-Henseleit buffer was used as the incubatory environment. Incubation of the sections was performed at a temperature of 37°C, in the gaseous mixture of oxygen and carbon dioxide used in the following proportion: 95% of O(2) and 5% of CO(2). Contractions of the aorta were registered with isotonic transducers (Letica Scientific Instruments). In the studies, we examined the influence of α(1)-adrenergic receptors (and their subtypes α(1A), α(1B), α(1D)) on the contractility of the aortic muscle in humans and swine by their stimulation or inhibition with some selected agonists or antagonists. This time, it was shown that the stimulation of α(1)-adrenergic receptors leads to contractions of the human and swine aortic muscle; the observed increase in the muscle tone may follow from the stimulation of all subtypes of alpha-1 receptor (α(1A), α(1B), α(1D)). All three subtypes of 1-adrenergic receptor are engaged in vasoconstriction, especially of α(1A) and α(1D) subtypes; the α(1B) subtype is less significant for aortic contractility. The contractile response of the aneurysmally-changed abdominal aorta in humans to agonists of α-adrenergic receptors was significantly less intense than that of the normal porcine aorta. It can be concluded that aneurysms influence the contractile response of the aorta.