Expression Of Aquaporin 2, Aquaporin 3 And Aquaporin 4 In Renal Medulla Of Bactrian Camel (Camelus Bactrianus)

Aquaporins (AQPs) are members of the aquaporin water channel family that play an important role in reabsorption of water from the renal tubular fluid to concentrate urine. Using immunohistochemical staining on paraffin sections, We studied expression of AQP2, AQP3 and AQP4 in renal medulla of Bactrian camel (Camelus bactrianus). The renal medulla of cattle (Bos taurus) acted as the control. Compared with the control, strong expression of AQP2 was observed at the apical plasma membrane and intracellular vesicles, in both the outer medullary collecting duct (OMCD) and the inner medullary collecting duct (IMCD) of camel. Strong expression of AQP3 was observed at the basolateral plasma membrane of the IMCD of camel. Strong AQP4 expression, however, was observed at the basolateral plasma membrane in the OMCD of camel. Moreover, moderate AQP4 expression was detected in endothelium of capillary in medullary region of camels, whereas very weak/absent expression was detected in endothelium of capillary of cattle. We concluded that expression of AQP2, AQP3 and AQP4 in the camel kidney showed some differences from cattle in renal trans-epithelial water transport. It may enhance our better understanding of special water metabolism mechanisms that enable camels to survive in extreme environments.