title: Analysis of accumulation of 99mTc-octreotide and 99mTc-EDDA/HYNIC-Tyr3-octreotide in the rat kidneys.
abstract: The aim of this study was to compare renal handling and distribution of (99m)Tc-octreotide and (99m)Tc-EDDA/HYNIC-Tyr(3)-octreotide (HYNIC-TOC) in rats. In kidney perfusion experiments, the renal clearance value of (99m)Tc-octreotide was three times lower than that of (99m)Tc-EDDA/HYNIC-TOC. The predominant renal excretion of (99m)Tc-EDDA/HYNIC-TOC was associated with a high and long-term renal accumulation up to 48 hrs. Microautoradiographic results indicated that (99m)Tc-EDDA/HYNIC-TOC was retained mainly in the renal medulla within the cells of the collecting ducts and in the surrounding tissue. Lower positivity was found in the proximal and distal tubular cells. We conclude that the mechanism of renal accumulation of somatostatin analogues renal accumulation is complex and that proximal tubular reabsorption is probably not the main mechanism for uptake of (99m)Tc-EDDA/HYNIC-TOC in the kidneys. The presence of the somatostatin receptors, differences in the tonicity level within kidneys and other possible mechanisms could participate in their renal accumulation.
authors.affiliation: Department of Biological and Medical Sciences, Charles University, Faculty of Pharmacy, Heyrovskeho 1203, 50005 Hradec Kralove, Czech Republic. kopecky@faf.cuni.cz
authors.forename: Martin
authors.initials: M
authors.lastname: Kopecky
authors.forename: Vladimir
authors.initials: V
authors.lastname: Semecky
authors.forename: Frantisek
authors.initials: F
authors.lastname: Trejtnar
authors.forename: Milan
authors.initials: M
authors.lastname: Laznicek
authors.forename: Alice
authors.initials: A
authors.lastname: Laznickova
authors.forename: Petr
authors.initials: P
authors.lastname: Nachtigal
authors.forename: Clemens
authors.initials: C
authors.lastname: Decristoforo
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Mather
authors.forename: Helmut R
authors.initials: HR
authors.lastname: Mäcke
mesh_terms: D000818:Animals; D007668:Kidney / Q000000981:diagnostic imaging* / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate; D015282:Octreotide / Q000031:analogs & derivatives* / Q000493:pharmacokinetics*; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics*; D011866:Radioisotope Renography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution
chemical_list: C493098:99mTc-octreotide; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C487389:technetium 99m EDDA-HYNIC-Tyr(3)-octreotide; D015282:Octreotide