ABSTRACT
Aquaporin (AQP) is a water channel protein that is of critical importance in the urinary concentrating process and the regulation of water balance in the kidney, and at least seven AQPs are expressed at distinct sites in the kidney. The common marmoset monkey is widely used as an experimental animal included in the primate order in the filed of renal system. However, nothing is known about the expression AQP in the common marmoset monkey kidney. The purpose of this study was to establish the distribution of AQP-1, AQP-2, AQP-3 and AQP-4 in the common marmoset monkey kidney. We used three male common marmoset monkeys (Callithrix jacchus) ranging in age from 2 to 3 years. AQP-1 was expressed in segments 1, 2 and 3 of the proximal tubule, particularly abundant in segment 1, and also observed in the descending thin limb of the medulla. AQP-2 immunoreactivity was observed in the apical plasma membrane of principal cells in the cortical and medullary collecting ducts. AQP-3 immunostaining was intense in the basolateral plasma membrane of connecting tubules as well as in the cortical and outer medullary collecting ducts. AQP-4 was expressed mainly in the cytoplasm of inner medullary collecting duct cells. These data suggest that AQPs of the common marmoset monkey kidney may play a similar role in urinary concentrating processes and the regulation of water balance to that of AQPs in rats, mice and humans.