Evaluation of Electrocardiographic Parameters, Thoracic Morphometry and Vertebral Heart Size in Clinically Normal Dogs

Background: The Vertebral Heart Size (VHS) method sets standards for the evaluation of dog’s heart size from the comparison of the cardiac dimension with the length of the thoracic vertebrae through radiographic study. Electrocardiogram (ECG) is widely used in veterinary medicine for the evaluation of electrical conduction system of the heart; however, the increase of duration and amplitude of the ECG waves can suggest the increase of cardiac chambers in dogs. The scientific literature presents electrocardiographic and VHS values for dogs of different breeds and sizes; however, there is little information on the correlation of these parameters. Therefore, the aim of this study was to evaluate the amplitude and duration of ECG waves, thoracic morphometry and VHS values, in order to correlate these parameters in clinically normal dogs.Materials, Methods & Results: Twenty healthy dogs (11 females and 9 males), without breed distinction, medium sized (14.46 ± 2.92 kg) and aged between 1 and 8 years, were evaluated through physical examination, digital ECG (frontal and precordial leads) and thorax X-ray in right lateral (RL), left lateral (LL) and ventrodorsal (VD) projections. Thoracic morphometry and VHS measurements were determined as previously described. Clinical and ECG parameters were compatible with the references in all dogs evaluated. Dogs (75%) presented thorax intermediate with the depth and width ratio (D/W ratio) > 1.0. Some individual VHS values were higher than the references and the mean VHS values in VD projection was higher than in RL and LL projections (n = 20; P < 0.05). Female and male dogs did not differ among the evaluated parameters. A positive correlation was observed between thoracic morphometry and body weight (r ≥ +0.70; P < 0.001) and a negative correlation was found between the D/W ratio and VD VHS (r = -0.62; P < 0.05). No significant correlations were observed between the age, ECG parameters, thoracic morphometry and VHS measurements.Discussion: The majority of dogs presented intermediate thorax, a common characteristic for healthy dogs of different breeds. Some dogs had higher VHS values in different projections, when compared to references. The same has been reported by others authors for diferent breeds. However, there is no consensus about VHS values for all sexes, breeds and physical conformations in dogs. In agreement with other authors, the mean value of VD VHS was higher in relation to RL and LL VHS; however, RL and LL VHS did not differ. Positive and significative correlations were observed between body weight and thorax depth, and between body weight and thorax width, confirming that larger dogs had greater thoracic measurements. The thorax type could influence the VHS, when this parameter is determined by VD projection, because was observed a negative and significative correlation between the D/W ratio and VD VHS. So, the dogs with a deeper thorax may have lower VHS values. The correlation between VHS measurements and duration and amplitude of the ECG waves was weak, possibly because the dogs evaluated had no clinical and radiographic signs of cardiomegaly. The results of this work indicated that dogs of medium size, without signs of cardiovascular or pulmonary disease, may have higher values for VHS; besides that, thoracic morphometry may alter VHS measurement obtained from the VD projection. In addition, ECG parameters were not influenced by thoracic morphometry and had no correlation with VHS measurements

Evaluation of Coagulation Parameters in Dogs with Overweight or Obesity

Background: Hemostatic alterations have already been well characterized in humans with body fat excess, being included in the list of obesity related comorbidities. Overweight and obesity are common in dogs; however, there is little information about the blood coagulation parameters in dogs with these conditions. The aim of this study was to compare hematological and coagulation parameters between lean dogs and overweight or obese dogs, including platelets count; prothrombin time (PT); activated partial thromboplastin time (aPTT), coagulation time (CT) and plasma fibrinogen concentration.Materials, Methods & Results: A total of 22 dogs (aged 1 to 10 years, neutered) were evaluated, 10 of them presented ideal body condition score (BCS 4-5) and formed the group 1 (control) and 12 were overweight or obese (BCS 7-9) and formed the group 2. The dogs were submitted to clinical evaluation and then to blood collection for the following laboratory tests: blood count (performed on automatic analyzer), quantification of plasma proteins by refractometry, determination PT, aPTT and plasma fibrinogen concentration using specific commercial kits, and CT by Lee-White method. Compared to group 1, group 2 presented a lower leukocytes and lymphocytes counts (P < 0.05) and a higher concentration of plasma fibrinogen (P = 0,026), but compatible with reference values. No difference was observed in the erythrogram, platelets count, total plasma protein concentration, PT, aPTT and CT between the groups. BCS was negatively correlated with leukocytes (r = -0.45) and lymphocytes (r = -0.60) counts and positively with plasma fibrinogen concentration (r = +0.56).Discussion: The reduction in lymphocytes led to a lower leukocytes count in the dogs of group 2. The migration of peripheral blood lymphocytes to adipose tissue has been reported in the early phase of the inflammatory process induced by obesity and could justify the reduction of circulating lymphocytes in overweight or obese dogs evaluated in this study; however, cytopathological assessment of adipose tissue was not performed. Fibrinogen has to be converted to fibrin for clot formation, so the concentration of this plasma protein is an important parameter for the evaluation of hemostasis. However, there are reports of increase in plasma fibrinogen as a result of infammatory processes. In group 2, formed by dogs with overweight or obese, the higher value of plasm fibrinogen concentration, associated with lower lymphocyte count, may suggest an early-stage inflammatory process. Similar results were described in obese humans, but also evidenced in obese dogs. Supporting this suggestion, the correlation analysis indicates that the higher the body fat excess (estimated by the BCS), the higher the fibrinogen concentration and the lower the lymphocyte count in evaluated dogs. Despite the higher concentration of plasma fibrinogen in group 2, no change was observed in the hemostasis of overweight or obese dogs, due to the normal values for platelets count, PT, aPTT and CT, excluding a hypercoagulability condition as already hypothesized by other authors for dogs and obese humans. The difference between our findings and the literature may be in the time of evolution of the disease, since we evaluated younger dogs. In conclusion, the body fat excess did not alter the erythrogram and the activity of the clotting factors, estimated by PT, aPTT and CT, but it interfered in the leukogram and increased the plasma concentration of fibrinogen in the evaluated dogs

Potassium Activates mTORC2-dependent SGK1 Phosphorylation to Stimulate ENaC: Role in Rapid Renal Responses to Dietary Potassium

BACKGROUND: Increasing evidence implicates the signaling kinase mTOR complex-2 (mTORC2) in rapid renal responses to changes in plasma potassium concentration [K+]. However, the underlying cellular and molecular mechanisms that are relevant in vivo for these responses remain controversial. METHODS: We used Cre-Lox-mediated knockout of rapamycin-insensitive companion of TOR (Rictor) to inactivate mTORC2 in kidney tubule cells of mice. In a series of time-course experiments in wild-type and knockout mice, we assessed urinary and blood parameters and renal expression and activity of signaling molecules and transport proteins following a K+ load via gavage. RESULTS: A K+ load rapidly stimulated epithelial sodium channel (ENaC) processing, plasma membrane localization, and activity in wild-type but not in knockout mice. Downstream targets of mTORC2 implicated in ENaC regulation (SGK1 and Nedd4-2) were concomitantly phosphorylated in wild-type but not knockout mice. We observed differences in urine electrolytes within 60 minutes, and plasma [K+] was greater in knockout mice within 3 hours of gavage. Renal outer medullary potassium (ROMK) channels were not acutely stimulated in wild-type or knockout mice, nor were phosphorylation of other mTORC2 substrates (PKC and Akt). CONCLUSIONS: The mTORC2-SGK1-Nedd4-2-ENaC signaling axis is a key mediator of rapid tubule cell responses to increased plasma [K+] in vivo. The effects of K+ on this signaling module are specific, in that other downstream mTORC2 targets such as PKC and Akt are not acutely affected, and ROMK and BK channels are not activated. These findings provide new insight into the signaling network and ion transport systems that underlie renal responses to K+in vivo

The CÃOCER Project: an Educational Approach for Cancer Prevention in Pet Animals

The CÃOCER projetct started four years ago and comprised several intra and extramural activities with the purpose to aware people of the importance of cancer in animals, focusing mainly in cancer prevention. With this intent, we provided a series of lectures for undergraduates and professionals of veterinary medicine. In addition, we participated in science fairs and exhibitions to disseminate the knowledge regarding cancer prevention for the population from Pirassununga, a city in the country of São Paulo State. Also, we conducted the first campaign of cancer prevention in animals named I Cãopanha of Cancer Prevention in Animals in which preventive physical clinical examinations were done on animals and educational material on cancer prevention was distributed. At last, it was also an objective of this work to perform a statistical survey of cancer cases in animals of Pirassununga. Some undergraduate students of Veterinary Medicine collaborated in this project with or without scholarships. Past four years since its inception, we believe that the project has achievedits initial goals and now our intention is to expand it. For this, we created a website(www.projetocaocer.com.br) that provides articles on cancer prevention in animals.We also wanted to increase the extension of the projetct activities, associating it withthe Brazilian Association of Veterinary Oncology (ABROVET) and the Support ResearchCenter in Veterinary Oncology from USP.O projeto CÃOCER há quatro anos compreende atividades intra e extramurais à USP com a finalidade de conscientizar a população sobre a importância dos cânceres em animais, focando em sua prevenção. Foram realizados ciclos de palestras para alunos de graduação em Medicina Veterinária e profissionais. Participamos de feiras de ciência e exposições para divulgação à população de Pirassununga, e realizamos a I Cãopanha de Prevenção de Câncer em Animais em que foram feitos exames clínicos nos animais e distribuído material educativo referente à prevenção de câncer. Por fim, ainda objetivou-se realizar um levantamento estatístico da casuística de animais portadores de neoplasias atendidos no Hospital Veterinário da FMVZ no campus de Pirassununga da USP. Colaboraram com este projeto diversos alunos de graduação em Medicina Veterinária da FZEA-USP e alunos do ensino médio que obtiveram bolsas pelo Programa de Pré-Iniciação Científica da USP. Passados quatro anos desdeseu início, o projeto atingiu seus objetivos iniciais e agora o intuito é expandi-lo. Para isso criamos um site (www.projetocaocer.com.br) que disponibiliza artigos sobreprevenção do câncer em animais. Pretendemos, também, aumentar as atividades extensionistas do projeto, junto à Associação Brasileira de Oncologia Veterinária e ao NAP de Oncologia Veterinária da Pró-Reitoria de Pesquisa da USP

Genomic and Nongenomic Effects of Aldosterone on Na+/H+ Exchanger and H+-ATPase in Proximal Tubule (S3): role of Cytosolic Calcium.

O presente estudo indica que o pHi basal do segmento S3 do túbulo proximal é 7.10 ? 0.007 (n = 444/2117), sendo a extrusão celular de H+ feita pelo trocador Na+/H+ (marjoritariamante) e pela H+-ATPase. Nossos resultados sugerem um papel do cálcio citosólico na regulação do processo de recuperação do pHi após carga ácida, mediada pelo trocador Na+/H+ e pela H+-ATPase. O trocador é estimulado por Aldosterona (10-12, 10-10 e 10-8 M) e inibido por Aldosterona (10-6 M) via ação genômica e não-genômica. Esses resultados são compatíveis com a estimulação do trocador por moderado aumento da [Ca2+]i citosólico (com Aldosterona 10-12 M) e sua inibição por pronunciado aumento da [Ca2+]i (com Aldosterona 10-6 M). A H+-ATPase é estimulada por Aldosterona em todas as doses utilizadas via ação genômica e não-genômica e esses resultados são coincidentes com um aumento da [Ca2+]i, dose dependente. Esses nossos achados são também compatíveis com a demonstração de uma ação hormonal não-genômica (após 1 ou 15 min) e genômica (após 1 hora) na [Ca2+]i, no trocador e na H+-ATPase. Adicionalmente, nossos resultados indicando que os efeitos hormonais genômicos ocorrem via receptor MR são coincidentes com nossos dados demonstrando a expressão desses receptores no segmento S3. Esses efeitos da Aldosterona que acabamos de descrever podem representar uma regulação fisiológica relevante, em condições de depleção e expansão de volume no animal intacto.The present study indicate that the basal pHi of proximal S3 segment is 7.10 ? 0.007 (n = 444/2117), being made the extrusion by of Na+/H+ exchanger (mainly) and H+-ATPase. Our results suggest a role for cell calcium in regulating the process of pHi recovery after the acid load induced by NH4Cl, mostly mediated by a basolateral Na+/H+ exchanger, and stimulated by Aldosterone (10-12, 10-10 e 10-8 M) and impaired by Aldosterone (10-6 M) via a genomic and nongenomic action. They are compatible with stimulation of the Na+/H+ exchanger by increases in cell calcium in the lower range (at Aldosterone 10-12 M) and inhibition at high cell calcium levels (at Aldosterone 10-6 M). The H+-ATPase is stimulated in all the used doses via a genomic and nongenomic action, this is coincident with the dose-dependent increase in [Ca2+]i. This finding is also compatible with the demonstration of a hormonal nongenomic (after 1 min or 15 min) and genomic (after 1 h) action on [Ca2+]i, on the Na+/H+ exchanger and on H+-ATPase. Our results indicating that the genomics effects are via MR receptor are in accordanc with our finding showing expression of the receptors in the proximal S3 segment of rat. These Aldosterone effects may represent physiologically relevant regulation in conditions of volume depletion or expansion in the intact animal

Action of ANP on the nongenomic dose-dependent biphasic effect of aldosterone on NHE1 in proximal S3 segment

The rapid (2 min) nongenomic effects of aldosterone (ALDO) and/or spironolactone (MR antagonist), RU 486 (GR antagonist), atrial natriuretic peptide (ANP) and dimethyl-BAPTA (BAPTA) on the intracellular pH recovery rate (pHirr) via NHE1 (basolateral Na+/H+ exchanger isoform), after the acid load induced by NH4Cl, and on the cytosolic free calcium concentration ([Ca2+](i)) were investigated in the proximal S3 segment isolated from rats, by the probes BCECF-AM and FLUO-4-AM, respectively. The basal pHi was 7.15+/-0.008 and the basal pHirr was 0.195+/-0.012 pH units/min (number of tubules/number of tubular areas = 16/96). Our results confirmed the rapid biphasic effect of ALDO on NHE1: ALDO (10(-12) M) increases the pHirr to approximately 59% of control value, and ALDO (10(-6)M) decreases it to approximately 49%. Spironolactone did not change these effects, but RU 486 inhibited the stimulatory effect and maintained the inhibitory effect. ANP (10(-6) M) or BAPTA (5 x 10(-5) M) alone had no significant effect on NHE1 but prevented both effects of ALDO on this exchanger. The basal [Ca2+](i) was 104+/-3 nM (15), and ALDO (10(-12) or 10(-6) M) increased the basal [Ca2+](i) to approximately 50% or 124%, respectively. RU 486, ANP and BAPTA decreased the [Ca2+](i) and inhibited the stimulatory effect of both doses of ALDO. The results suggest the involvement of GR on the nongenomic effects of ALDO and indicate a pHirr-regulating role for [Ca2+](i) that is mediated by NHE1, stimulated/impaired by ALDO, and affected by ANP or BAPTA with ALDO. The observed nongenomic hormonal interaction in the S3 segment may represent a rapid and physiologically relevant regulatory mechanism in the intact animal under conditions of volume alterations. (C) 2011 Elsevier Ltd. All rights reserved.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Pesquisas (CNPq)Conselho Nacional de Pesquisas (CNPq

Direct action of aldosterone on bicarbonate reabsorption in in vivo cortical proximal tubule

Pergher PS, Leite-Dellova D, de Mello-Aires M. Direct action of aldosterone on bicarbonate reabsorption in in vivo cortical proximal tubule. Am J Physiol Renal Physiol 296: F1185-F1193, 2009. First published February 18, 2009; doi:10.1152/ajprenal.90217.2008.-The direct action of aldosterone (10(-12) M) on net bicarbonate reabsorption (J(HCO3)(-)) was evaluated by stationary microperfusion of an in vivo middle proximal tubule (S2) of rat kidney, using H ion-sensitive microelectrodes. Aldosterone in luminally perfused tubules caused a significant increase in J(HCO3)(-) from a mean control value of 2.84 +/- 0.08 [49/19 (n degrees of measurements/n degrees of tubules)] to 4.20 +/- 0.15 nmol.cm(-2).s(-1) (58/10). Aldosterone perfused into peritubular capillaries also increased J(HCO3)(-), compared with basal levels during intact capillary perfusion with blood. In addition, in isolated perfused tubules aldosterone causes a transient increase of cytosolic free calcium ([Ca(2+)](i)), monitored fluorometrically. In the presence of ethanol ( in similar concentration used to prepare the hormonal solution), spironolactone (10(-6) M, a mineralocorticoid receptor antagonist), actinomycin D (10(-6) M, an inhibitor of gene transcription), or cycloheximide (40 mM, an inhibitor of protein synthesis), the J(HCO3)(-) and the [Ca(2+)](i) were not different from the control value; these drugs also did not prevent the stimulatory effect of aldosterone on J(HCO3)(-) and on [Ca(2+)](i). However, in the presence of RU 486 alone [10(-6) M, a classic glucocorticoid receptor (GR) antagonist], a significant decrease on J(HCO3)(-) and on [Ca(2+)](i) was observed; this antagonist also inhibited the stimulatory effect of aldosterone on J(HCO3)(-) and on [Ca(2+)](i). These studies indicate that luminal or peritubular aldosterone (10(-12) M) has a direct nongenomic stimulatory effect on J(HCO3)(-) and on [Ca(2+)](i) in proximal tubule and that probably GR participates in this process. The data also indicate that endogenous aldosterone stimulates J(HCO3)(-) in middle proximal tubule

Genomic and nongenomic dose-dependent biphasic effect of aldosterone on Na(+)/H(+) exchanger in proximal S3 segment: role of cytosolic calcium

Leite-Dellova DC, Oliveira-Souza M, Malnic G, Mello-Aires M. Genomic and nongenomic dose-dependent biphasic effect of aldosterone on Na(+)/H(+) exchanger in proximal S3 segment: role of cytosolic calcium. Am J Physiol Renal Physiol 295: F1342-F1352, 2008. First published August 20, 2008; doi:10.1152/ajprenal.00048.2008.-The effects of aldosterone on the intracellular pH recovery rate (pHirr) via Na(+)/H(+) exchanger and on the [Ca(2+)](i) were investigated in isolated rat S3 segment. Aldosterone [10(-12), 10(-10), or 10(-8) M with 1-h, 15- or 2-min preincubation (pi)] caused a dose-dependent increase in the pHirr, but aldosterone (10(-6) M with 1-h, 15- or 2-min pi) decreased it (these effects were prevented by HOE694 but not by S3226). After 1 min of aldosterone pi, there was a transient and dose-dependent increase of the [Ca(2+)](i) and after 6-min pi there was a new increase of [Ca(2+)](i) that persisted after 1 h. Spironolactone, actinomycin D, or cycloheximide did not affect the effects of aldosterone (15 -or 2-min pi) but inhibited the effects of aldosterone (1-h pi) on pHirr and on [Ca(2+)](i). RU 486 prevented the stimulatory effect of aldosterone (10(-12) M, 15 -or 2-min pi) on both parameters and maintained the inhibitory effect of aldosterone (10(-6) M, 15- or 2-min pi) on the pHirr but reversed its stimulatory effect on the [Ca(2+)](i) to an inhibitory effect. The data indicate a genomic (1 h, via MR) and a nongenomic action (15 or 2 min, probably via GR) on [Ca(2+)](i) and on the basolateral NHE1 and are compatible with stimulation of the NHE1 by increases in [Ca(2+)](i) in the lower range (at 10(-12) M aldosterone) and inhibition by increases at high levels (at 10(-6) M aldosterone) or decreases in [Ca(2+)](i) (at 10(-6) M aldosterone plus RU 486).FAPESP Fundacao de Amparo a Pesquisa do Estado de Sao PauloFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq Conselho Nacional de Pesquisa

Physical and electrocardiographic evaluation of horses used for wagon traction

ABSTRACT The objective of this research was to evaluate the electrocardiogram (ECG) of horses used for wagon traction and to compare the results with the parameters obtained from inactive horses or horses submitted to a training routine. Fifty-six 3-15-year-old healthy horses (22 females and 34 males) were divided into three groups: control (without a work routine; N=21), wagon traction (N=25) and athlete (N=10) and submitted to physical examination and ECG (at rest). The rhythm, heart rate (HR), amplitude and duration of ECG waveforms and intervals were obtained from the frontal plane and base-apex leads. Heart score (HS) was calculated using the arithmetic mean of QRS duration in LI, LII and LIII. Measurements of ECG waves were smaller in control group, in comparison with wagon traction and athlete groups, suggesting that exercise can change ECG. Similar results were observed in the wagon traction and athlete groups, but the electrophysiological adjustments to exercise were not the same for these groups