| Research Abstract |
1. Cytochrome P450 represents the third metabolic pathway of arachidonic acid giving rise to several biologically active compounds, such as 19 HETE, 20 HETE and EETs and their corresponding DHETs. The kidney is the rich source of these metabolites and these metabolites have a wide and contrasting spectrum of biological and renal effects, from vasodilation to vasoconstriction and from inhibition to stimulation of Na-K-ATPase, . Their relative production rates may influence not only renal hemodynamics but also pro- and anti-hypertensive mechanisms of hypertension.
2. The effect of insulin on intracellular pH reguration in microperfused rabbit S2 proximal straight tubules were examined. According to our results, insulin stimulates luminal Na-H exchange.
3. The cDNA encodes 365 amino acids with 97% sequence identify to mouse EP3a receptor (EP3alpha) were isolated. Specific binding of [^3H]PGE_2 was found in COS-7 cells transfected with the cDNA (Kd=3.2nM) and was displaced with unlabeled pro
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staglandins in the order of PGE_2=PGE_1>>PGF_<2alpha>>PGD_2. In situ hybridization revealed expression of rEP_3 receptor principally in the medulla. Moreover, the reverse transcription and polymerase chain reaction (RT-PCR) using dissected nephron segments showed the receptor expression specifically in medullary and cortical thick ascending limbs of Henle's loop, cortical collecting ducts and inner medullary collecting ducts. Moreover, another isoform of EP_3 subtype (EP_<3beta>) with different carboxyl-terminal domains have been characterized.
4. A cDNA encoding MDCK-type chloride channel (RKCL) was isolated. Electrophysiological analysis using Xenopus oocyte expression system showed the functional character of chloride channel. RKCL mRNA is widely expressed in various tissues. In situ hybridization revealed that RKCL mRNA is more expressed in the renal medulla and papilla than in the cortex. RT-PCR showed that main sites of the RKCL mRNA expression are ascending thin limbs of Henle's loop and inner medullary collecting ducts. Under dehydration, renal RKCL mRNA expression level was not statistically changed up to five days. Less
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