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EFFECTS OF SINGLE DOSE of parecoxib ON FUNCTION, CELLULAR INJURY AND INFLAMMATORY RESPONSE On THE kidney OF RATS SUBMITTED TO ACUTE HEMORRHAGE.

Grant number: 11/10122-0
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): August 01, 2011
Effective date (End): July 31, 2013
Field of knowledge:Health Sciences - Medicine - Surgery
Principal researcher:Yara Marcondes Machado Castiglia
Grantee:Vitor Vasquez dos Santos
Home Institution: Faculdade de Medicina (FMB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Introduction: Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in reducing postoperative pain. The new COX-2 selective NSAIDs were developed to reduce the undesirable effects with similar analgesic efficacy to conventional NSAIDs. Parecoxib is the only COX-2 selective inhibitor available for parenteral use. By inhibiting the production of prostaglandins, may contribute to the decline of renal blood flow (RBF) and glomerular filtration rate (GFR), especially in situations of decrease in renal perfusion, such as hemorrhage and hypovolemia. Inflammation plays an important role in the pathophysiology of ischemic acute renal injury. Renal ischemia stimulates the production, by endothelial and tubular cells, of inflammatory mediators such as cytokines (IL-I, IL-6 and TNF-±), responsible for initiation and progression of inflammation and renal injury. Objective: To evaluate whether pretreatment with parecoxib affects the function, cell damage and inflammatory response of kidney in rats subjected to acute hemorrhage during surgery. Methods: After approval from the Animal Experimentation Ethics Commission, College of Medicine of Botucatu, UNESP, the study will be developed with male Wistar rats weighting > 250g. After anesthesia with sevoflurane 4%, the animals will be intubated and divided randomly into four groups: G1 (n = 11): placebo/ without hemorrhage, G2 (n = 11): parecoxib/ without hemorrhage; G3 (n = 11): placebo/ hemorrhage, and G4 (n = 11): parecoxib/ hemorrhage. Rats will receive sevoflurane in concentration needed to surgical manipulation, kept in artificial ventilation and body temperature between 37 and 38 ° C with thermal bags preheated. It'll be dissected right internal jugular vein, with immediately infusion bolus dose of parecoxib (20 mg/ kg in 2 ml/ kg iv) or placebo (normal saline solution 2ml/ kg iv) according to the distribution of groups. All groups will receive 1 mg of sodium para-aminohippurate (PAH) solution and 0.5 mg of sodium iothalamate (IOT) as priming dose, and maintained with continuous infusion of PAH solution 1 mg/ h, and IOT 0.25 mg/ h until the end of the experiment. It'll be dissected the left carotid artery for mean blood pressure and heart rate measures. After 30 minutes of administration of PAH and IOT primes and the bolus of parecoxib or placebo, the groups of animals with hemorrhage will suffer bleeding corresponding to 30% of blood volume through the carotid artery, performed on three different moments with an interval of 10 minutes between them. In each moment will be removed 10% of blood volume. The volume of blood from the first bleeding will be separated for hematocrit and concentrations of PAH and IOT determinations (time M1). Fifty minutes after the third bleeding (time M2), it'll be collected blood sample to determine concentrations of PAH and IOT, hematocrit and serum cytokines (TNF-±, IL-1, IL-6 and IL-10). The clearance of PAH (CPAH) will be used to estimate effective renal plasma flow and clearance of IOT (CIOT) to estimate the glomerular filtration rate. In M2, immediately after collection of blood sample, rats will be subject to laparotomy for bilateral nephrectomy and, until under anesthesia, they'll be sacrificed with intravenous potassium chloride 19.1%. Both kidneys collected from each animal will be immediately divided into two halves by longitudinal section. Half of each kidney will be separated for histological preparation. The pathologist who will observe the histological changes will not know which group the kidneys belong to. The other two halves remaining will be macerated, homogenized and centrifuged, resulting in the supernatant of kidney protein for determination of cytokines (TNF-±, IL-1, IL-6 and IL-10) using ELISA kits.

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