Effects of chronic acetazolamide administration on gas exchange and acid-base control in pulmonary circulation in exercising horses

P>Reasons for performing study:Carbonic anhydrase (CA) catalyses the hydration/dehydration reaction of CO(2) and increases the rate of Cl- and HCO(3)- exchange between the erythrocytes and plasma. Therefore, chronic inhibition of CA has a potential to attenuate CO(2) output and induce greater metabolic and respiratory acidosis in exercising horses.Objectives:To determine the effects of Carbonic anhydrase inhibition on CO(2) output and ionic exchange between erythrocytes and plasma and their influence on acid-base balance in the pulmonary circulation (across the lung) in exercising horses with and without CA inhibition.Methods:Six horses were exercised to exhaustion on a treadmill without (Con) and with CA inhibition (AczTr). CA inhibition was achieved with administration of acetazolamide (10 mg/kg bwt t.i.d. for 3 days and 30 mg/kg bwt before exercise). Arterial, mixed venous blood and CO(2) output were sampled at rest and during exercise. An integrated physicochemical systems approach was used to describe acid base changes.Results:AczTr decreased the duration of exercise by 45% (P < 0.0001). During the transition from rest to exercise CO(2) output was lower in AczTr (P < 0.0001). Arterial PCO(2) (P < 0.0001; mean +/- s.e. 71 +/- 2 mmHg AczTr, 46 +/- 2 mmHg Con) was higher, whereas hydrogen ion (P = 0.01; 12.8 +/- 0.6 nEq/l AczTr, 15.5 +/- 0.6 nEq/l Con) and bicarbonate (P = 0.007; 5.5 +/- 0.7 mEq/l AczTr, 10.1 +/- 1.3 mEq/l Con) differences across the lung were lower in AczTr compared to Con. No difference was observed in weak electrolytes across the lung. Strong ion difference across the lung was lower in AczTr (P = 0.0003; 4.9 +/- 0.8 mEq AczTr, 7.5 +/- 1.2 mEq Con), which was affected by strong ion changes across the lung with exception of lactate.Conclusions:CO(2) and chloride changes in erythrocytes across the lung seem to be the major contributors to acid-base and ions balance in pulmonary circulation in exercising horses.

Toxic acute hepatitis associated to the administration of prostaglandin in a dog

A prostaglandina F2a pode ser usada em caes para aumentar o volume do ejaculado em casos de inseminação artificial, criopreservação seminal ou biotecnologias de reprodução. Os efeitos colaterais após a administração da PGF2a, como taquicardia, salivação, emese, diarréia e convulsões geralmente são relacionadas com a dose utilizada. Esse trabalho objetiva relatar a ocorrência de hepatite tóxica aguda após a administração de PGF2a em um cão, e discutir a importância de se utilizar essa droga com cautela nessa espécie.

Participation of alpha-1 and alpha-2 adrenoceptors of the lateral hypothalamic area in water intake, and renal sodium, potassium and urinary Volume excretion induced by central administration of angiotensin II

The circumventricular structures and the lateral hypothalamus (LH) have been shown to be important for the central action of angiotensin II (ANGII) on water and electrolyte regulation. Several anatomical findings have demonstrated neural connection between circumventricular structures and the LH, the present experiments were conducted to investigate the role of the alpha-adrenergic antagonists and agonistic injected into the LH on the water intake, sodium and potassium excretion elicited by injections of ANGII into the lateral ventricle (LV), the water intake was measured every 30 min over a period of 120 min. The sodium, potassium and urinary volume were measured over a period of 120 min in water-loaded rats. The injection of ANGII into the LV increased the water intake, which was reduced by previous injection of clonidine (an alpha-2-adrenergic agonist) into the LH. The injection of yohimbine (an alpha-2-adrenergic antagonist) and prazosin (an alpha-l-adrenergic antagonist) into the LH, which was done before injecting ANGII into the LV, also reduced the water intake induced by ANGII. The injection of ANGII into the LV reduced the sodium, potassium and urinary volume. Previous treatment with clonidine attenuated the action of ANGII in reducing the sodium, potassium and urinary volume, whereas previous treatment with yohimbine attenuated the effects of ANGII but with less intensity than that caused by clonidine. Previous treatment with prazosin increased the inhibitory effects of ANGII in those parameters. The injection of yohimbine and prazosin, which was done before the injection of clonidine, attenuated the effect of clonidine on the ANGII mechanism. The results of this study led us to postulate that when alpha-2-adrenergic receptors are blocked, the clonidine may act on the imidazoline receptors to produce its effects on the ANGII mechanism. We may also conclude that the LH is involved with circumventricular structures, which present excitatory and inhibitory mechanisms. Such mechanisms are responsible for regulating the renal excretion of sodium, potassium and water, (C) 2000 Elsevier B.V.

Vascular adaptive responses to physical exercise and to stress are affected differently by nandrolone administration

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of reduction in egg shedding of gastrointestinal nematodes in cattle following administration of anthelmintics

No intuito de avaliar o tempo necessário para redução dos valores de OPG visando identificar o início de atuação dos anti-helmínticos, cinco grupos de novilhos, naturalmente infectados por nematódeos gastrintestinais foram tratados com moxidectina, ivermectina, fosfato de levamisol e sulfóxido de albendazol. O levamisol promoveu redução no número de ovos de nematódeos eliminados nas fezes (R-OPG) de 97,4% 24 horas após a aplicação, a moxidectina de 98,3% após 36 horas, e o sulfóxido de albendazol de 95,9% após 36 horas. Foi registrada a presença de Cooperia spp. e Haemonchus spp. com resistência a ivermectina. A contagem de OPG realizada aos sete dias pós-tratamento apresentou resultados similares aos obtidos nas contagens realizadas 10 e 14 dias após a aplicação dos anti-helmínticos avaliados, demonstrando que o intervalo adequado entre o tratamento anti-helmíntico e o exame para verificar a redução do OPG pode ser de 7 dias.

The influence of local administration of simvastatin in calvarial bone healing in rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chronic administration of Abarema cochliacarpos attenuates colonic inflammation in rats

Inflammatory bowel diseases are characterized by a chronic clinical course of relapse and remission associated with self-destructive inflammation of the gastrointestinal tract. Active extracts from plants have emerged as natural potential candidates for its treatment. Abarema cochliacarpos (Gomes) Barneby & Grimes, Fabaceae (Barbatimão), is a native medicinal plant in to Brazil. Previously we have demonstrated in an acute colitis model a marked protective effect of a butanolic extract, so we decided to assess its anti-inflammatory effect in a chronic ulcerative colitis model induced by trinitrobenzensulfonic acid (TNBS). Abarema cochliacarpos (150 mg/day, v.o.) was administered for fourteen consecutive days. This treatment decreased significantly macroscopic damage as compared with TNBS. Histological analysis showed that the extract improved the microscopic structure. Myeloperoxidase activity (MPO) was significantly decreased. Study of cytokines showed that TNF-α was diminished and IL-10 level was increased after Abarema cochliacarpos treatment. In order to elucidate inflammatory mechanisms, expression of cyclooxygenase (COX)-2 and nitric oxide synthase (iNOS) were studied showing a significant downregulation. In addition, there was reduction in the JNK and p-38 activation. Finally, IκB degradation was blocked by Abarema cochliacarpos treatment being consistent with an up-regulation of the NF-kappaB-binding activity. These results reinforce the anti-inflammatory effects described previously suggesting that Abarema cochliacarpos could provide a source for the search for new anti-inflammatory compounds useful in ulcerative colitis treatment.

Effects of the administration of a catalase inhibitor into the fourth cerebral ventricle on cardiovascular responses in spontaneously hypertensive rats exposed to sidestream cigarette smoke

OBJECTIVE: ,,,,,Previous studies have demonstrated a relationship between brain oxidative stress and cardiovascular regulation. We evaluated the effects of central catalase inhibition on cardiovascular responses in spontaneously hypertensive rats exposed to sidestream cigarette smoke. ,,,, ,,,, ,,,,,METHODS: ,,,,,Male Wistar Kyoto (WKY) rats and spontaneously hypertensive rats (SH) (16 weeks old) were implanted with a stainless steel guide cannula leading into the fourth cerebral ventricle (4th V). The femoral artery and vein were cannulated for arterial pressure and heart rate measurement and drug infusion, respectively. The rats were exposed to sidestream cigarette smoke for 180 minutes/day, 5 days/week for 3 weeks (CO: 100-300 ppm). The baroreflex was tested using a pressor dose of phenylephrine (8 μg/kg, bolus) and a depressor dose of sodium nitroprusside (50 μg/kg, bolus). Cardiovascular responses were evaluated before and 5, 15, 30 and 60 minutes after injection of a catalase inhibitor (3-amino-1,2,4-triazole, 0.001 g/100 μL) into the 4th V. ,,,, ,,,, ,,,,,RESULTS: ,,,,,Vehicle administration into the 4th V did not affect the cardiovascular response, whereas administration of the central catalase inhibitor increased the basal HR and attenuated the bradycardic peak (p<0.05) to a greater extent in WKY rats exposed to sidestream cigarette smoke than in WKY rats exposed to fresh air. However, in spontaneously hypertensive rats, the effect of the catalase inhibitor treatment was stronger in the fresh air condition (p<0.05). ,,,, ,,,, ,,,,,CONCLUSION: ,,,,,Administration of a catalase inhibitor into the 4th V combined with exposure to sidestream cigarette smoke has a stronger effect in WKY rats than in SH rats.

Adrenoceptors of the medial septal area modulate water intake and renal excretory function induced by central administration of angiotensin II

We investigated the role of alpha-adrenergic antagonists and clonidine injected into the medial septal area (MSA) on water intake and the decrease in Na+, K+ and urine elicited by ANGII injection into the third ventricle (3rdV). Male Holtzman rats with stainless steel cannulas implanted into the 3rdV and MSA were used. ANGII (12 nmol/µl) increased water intake (12.5 ± 1.7 ml/120 min). Clonidine (20 nmol/µl) injected into the MSA reduced the ANGII-induced water intake (2.9 ± 0.5 ml/120 min). Pretreatment with 80 nmol/µl yohimbine or prazosin into the MSA also reduced the ANGII-induced water intake (3.0 ± 0.4 and 3.1 ± 0.2 ml/120 min, respectively). Yohimbine + prazosin + clonidine injected into the MSA abolished the ANGII-induced water intake (0.2 ± 0.1 and 0.2 ± 0.1 ml/120 min, respectively). ANGII reduced Na+ (23 ± 7 µEq/120 min), K+ (27 ± 3 µEq/120 min) and urine volume (4.3 ± 0.9 ml/120 min). Clonidine increased the parameters above. Clonidine injected into the MSA abolished the inhibitory effect of ANGII on urinary sodium. Yohimbine injected into the MSA also abolished the inhibitory effects of ANGII. Yohimbine + clonidine attenuated the inhibitory effects of ANGII. Prazosin injected into the MSA did not cause changes in ANGII responses. Prazosin + clonidine attenuated the inhibitory effects of ANGII. The results showed that MSA injections of alpha1- and alpha2-antagonists decreased ANGII-induced water intake, and abolished the Na+, K+ and urine decrease induced by ANGII into the 3rdV. These findings suggest the involvement of septal alpha1- and alpha2-adrenergic receptors in water intake and electrolyte and urine excretion induced by central ANGII.

Toxicological evaluation of long-term intravenous administration of amitraz in horses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparison of behavioral and clinical effects of intravenous amitraz or romifidine administration in horses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)