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Research interests:
Expression and regulation of the renin-angiotensin system
Research interests: Expression and regulation of the renin-angiotensin system
The renin-angiotensin system (RAS) has long been considered to be a circulating hormonal system in the regulation of blood pressure, fluid and electrolyte balance. The endocrine RAS has several key components namely, the precursor angiotensinogen derived from the liver, the enzymes renin and angiotensin converting enzyme derived from the kidney and lung respectively along with the physiologically active product, angiotensin II as well as its specific receptor subtypes, type I (AT1) and type II (AT2). Recently, a shift from endocrine RAS to paracrine/autocrine RAS control of tissue functions is being emphasized. The presence of key RAS component genes indispensable for the existence of an intrinsic RAS, notably angiotensinogen and renin has been demonstrated in a variety of tissues. The widespread presence of locally formed RAS components in multiple tissues has led to the notion for a local RAS which may play a paracrine or autocrine role in individual tissues of physiological importance.
Two of such local RAS in the pancreas and in the epididymis are intensively studying in my laboratory. The pancreatic RAS may play a role in the regulation of pancreatic blood flow and ductal anion secretion which could be important for the exocrine or endocrine functions of the pancreas. The epididymal RAS may play a role in the regulation of electrolyte secretion, and hence fluid secretion which affects the epididymal and sperm functions. My current research is to study the expression and regulation of the local RAS in the pancreas and in the epididymis by various factors in acute or chronic conditions. Regulated expression of the local RAS is studied using cellular and molecular biological approaches. The significance of altered expression of local RAS, for instance in the pancreas and epididymis, may shed light on the understanding of physiological and pathophysiological aspects of the pancreatic and epididymal functions.
Selected Publications:
* Leung, P.S., W.P. Chan, C. Sernia. Expression and localization of the reinin-angiotensin system in the rat pancreas (1999). Journal of Endocrinology 160, 13-19.
* Leung, P.S., Yao, X.Q., Chan, H.C., Fu, L.X.M., Wong, P.Y.D. Differential gene expression of angiotensin II receptor subtypes in the epididymides of mature and immature rats (1998). Life Sciences 62, 461-468.* Leung, P.S., Chan, H.C., Fu, L.X.M., Zhou, W.L., Wong, P.Y.D. Angiotensin II receptors, AT1 and AT2 in the rat epididymis: immunocytochemical and electrophysiological studies (1997). Biochimica et Biophysica Acta 1357, 65-72.
* Leung, P.S., Shaw, C., Irvine, G.B. Quantitation and chromatographic characterization of neuropeptide F (NPF) in molluscan nervous tissue using region-specific antisera (1994). General and Comparative Endocrinology 93, 288-293.
* Leung, P.S., Shaw, C., Maule, A.G., Thim, L., Johnston, C.F., Irvine, G.B. The primary structure of neuropeptide F (NPF) from the garden snail, Helix aspersa (1992). Regulatory Peptides 41, 71-81.
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