| Ischeamia - reperfusion after pancreas transplantation may increase the risk of graft pancreatitis. The pathogenesis of I/R is multi-factorial , while the diverse physiological properties of adenosine, coupled with increase concentration in the ischaemic tissues, suggest that it may play an important role in regulating and protecting the tissues in the setting of ischaemia and reperfusion. Administration of exogenous adenosine could ameliorate graft organ reperfusion injury through a number of mechanisms. This study was design to investigate the effect of exogenous adenosine on rat pancreas during Ischemia - reperfusion Injury.MethodsUsing model of Ischemia - reperfusion at tail pancreas of rats. The levels of high - energy nucleotides ATP, ADP, AMP determined with HPLC, activities of AMY and histological and electron microscope changes were observed in different groups. 35 rats were divided into 5 group randomly - control group ( group 1) ; Ischemia - reperfusion group ( group 2 : Ischemiaed 30mins followed reperfusioned 90mins) ; ADO treated group (group 3) ;8 - PT treated group (group 4) ; DPCPX treated group (group 5).Resultsthe levels of ATP ,TAN (ATP + ADP + AMP) ,EC ((ATP + I/ 2ADP)/TAN) of pancreas tissues were decreased rapidly in group I/ R ,and increased in group ADO,8 -PT, DPCPX. ATP(209947 ?12674/135135 ±27059 */177895 ±49383*/247655 ±89755/247363 ± 36233 * p < 0. 05); TAN (984556 ± 104028/537196 ± 34064 */ 6987756 ±3009 */663785 ± 107284/7347117 ±3152 * p <0. 05) ,EC (0.39 ±0.02/0. 38 ±0.02*/0.39 ±0.04* * p < 0. 05 ) , AMY (395. 71 ± 50. 12/2325. 002 ±50. 10*/2034. 28 ± 271. 83 */2363. 422 ± 19. 24 / 1896. 854 ± 71. 86 * * p <0. 05 ) Adenosine is able to modify the nucleotide content of Ischemia - reperfusioned pancreas of rats. As compared with group ADO, DPCPX group have no more damage in histological and electron microscope changes.DiscussionIscheamia - reperfusion after pancreas transplantation may increase the risk of graft pancreatitis. The pathogenesis of I/R is multi-factorial , involving neutrophil mediated injury, generation of cytotoxic derived free radicals, a progressive decrease in microvascular flow to the reperfused bed, alteration in calcium homeostasis, and ongoing depletion of high - energy phosphate stores. The diverse physiological properties of adenosine, coupled with increase concentration in the is-chaemic tissues, suggest that it may play,an important role in regulating and protecting the tissues in the setting of ischaemia and reperfusion. Administration of exogenous adenosine could ameliorate graft or-gan reperfusion injury through a number of mechanisms. Adenosine could reduce neutrophil mediated cellular injury during reperfusion by inhibiting neutrophil adhesion to endothelial cells and by decreasing the production of free radicals and proteolytic enzymes. The potent ar-teriolar vasodilator properties of adenosine could reverse the effects of various vasoconstriction substances present in the reperfusion bed. Furthermore, restoration of the and - inflammatory and vasodilator functions of endothelial cells through ATP repletion and oxygen delivery would maintain regional blood flow following reperfusion. Adenosine could also reduce free radical mediated injury by inhibiting super-oxide anion release from neurophils, decrease catecholamine release, and reduce lipid peroxidatoin. Adenosine also blocks calcium dependent channels and may therefore restore intracellular calcium homeosta-sis. Finally, adenosine could enhance intracellular ATP levels via the salvage pathway while conserving utilization through its negative ino-tropic effect.The protective effects of adenosine on I/R could be mediated through activation of extracellular receptors or through activation a non - receptor mechanism such as replenishment of ATP pool. The receptors are classified as A1, A2( A2A , A2B) , A3. Regulatory G proteins are involved in the signal transduction for the receptors resulting in activation or inhibition of adenylate cyclase. Respectl... |
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