TY - JOUR
T1 - Receptor-mediated endocytosis of A14-125I-insulin by the nonfiltering perfused rat kidney
AU - Sato, Hitoshi
AU - Yoshioka, Kuniaki
AU - Terasaki, Tetsuya
AU - Tsuji, Akira
N1 - Funding Information:
This study was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education. Science and Culture of Japan. Project Research Fund from the Oraduate School of Natural 3cience and Technology, Kanazawa University, and grants from Takeda Science Foundation and Nakatomi Foundation. The authors thank Mr. Saburo Okabe. the Meat Inspection ('eater of Kanazawa City, for graciously providing us with fresh bovine erylhrocytes.
PY - 1991/4/9
Y1 - 1991/4/9
N2 - The mechanism of insulin uptake and/or degradation in the peritubular circulation of the kidney was investigated using nonfiltering perfused rat kidneys, in which glomerular filtration was sufficiently reduced. After perfusion of A14-125I-insulin in the nonfiltering kidney for designated intervals, the acid-wash technique was employed to separately measure the acid-extractable and acid-resistant A14-125I-insulin, which were quantitated by HPLC and TCA-precipitability. HPLC profiles showed that the nonfiltering kidney metabolizes A14-125I-insulin only to a small extent during 1-h perfusion, suggesting that the peritubular clearance of A14-125I-insulin was not due to extracellular degradation but for the most part to uptake by the kidney. Acid-extractable A14-125I-insulin rapidly increased with time and reached pseudo-equilibrium with perfusate at approx. 10 min, whereas acid-resistant A14-125I-insulin increased continuously. An endocytosis inhibitor, phenylarsine oxide, inhibited significantly the acid-resistant A14-125I-insulin with no change in acid-extractable A14-125I-insulin, suggesting that the peritubular uptake of A14-125I-insulin largely represents endocytosis of the peptide into the intracellular space. Moreover, both the acid-extractable and acid-resistant A14-125I-insulin were significantly decreased in the presence of unlabeled insulin (1 μM). These lines of evidence suggest that insulin is taken up by the nonfiltering perfused kidney via receptor-mediated endocytosis (RME), which possibly occurs at the basolateral side of renal tubular cells, and that the peritubular clearance of insulin is largely accounted for by this mechanism.
AB - The mechanism of insulin uptake and/or degradation in the peritubular circulation of the kidney was investigated using nonfiltering perfused rat kidneys, in which glomerular filtration was sufficiently reduced. After perfusion of A14-125I-insulin in the nonfiltering kidney for designated intervals, the acid-wash technique was employed to separately measure the acid-extractable and acid-resistant A14-125I-insulin, which were quantitated by HPLC and TCA-precipitability. HPLC profiles showed that the nonfiltering kidney metabolizes A14-125I-insulin only to a small extent during 1-h perfusion, suggesting that the peritubular clearance of A14-125I-insulin was not due to extracellular degradation but for the most part to uptake by the kidney. Acid-extractable A14-125I-insulin rapidly increased with time and reached pseudo-equilibrium with perfusate at approx. 10 min, whereas acid-resistant A14-125I-insulin increased continuously. An endocytosis inhibitor, phenylarsine oxide, inhibited significantly the acid-resistant A14-125I-insulin with no change in acid-extractable A14-125I-insulin, suggesting that the peritubular uptake of A14-125I-insulin largely represents endocytosis of the peptide into the intracellular space. Moreover, both the acid-extractable and acid-resistant A14-125I-insulin were significantly decreased in the presence of unlabeled insulin (1 μM). These lines of evidence suggest that insulin is taken up by the nonfiltering perfused kidney via receptor-mediated endocytosis (RME), which possibly occurs at the basolateral side of renal tubular cells, and that the peritubular clearance of insulin is largely accounted for by this mechanism.
KW - (Rat)
KW - Basolateral endocytosis
KW - Insulin receptor
KW - Nonfiltering perfused kidney
KW - Peritubular clearance
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U2 - 10.1016/0304-4165(91)90213-Z
DO - 10.1016/0304-4165(91)90213-Z
M3 - Article
C2 - 2015267
AN - SCOPUS:0025727516
VL - 1073
SP - 442
EP - 450
JO - Biochimica et Biophysica Acta - General Subjects
JF - Biochimica et Biophysica Acta - General Subjects
SN - 0006-3002
IS - 3
ER -