Specific receptors for beta-endorphin on mesangial cells.
beta-Endorphin is an endogenous opioid considered to be a modulator of immune injury. We studied the binding of [125I]beta-endorphin on cultured rat mesangial cells at 4 and 37 degrees C. The results were analyzed by computer program (Ligand). Incubation of rat mesangial cells with unlabeled beta-endorphin displaced [125I]beta-endorphin in a concentration-dependent manner. The binding of [125I]beta-endorphin was not affected by either opiate agonists or antagonists. Saturation studies at 37 degrees C revealed that beta-endorphin binding was time dependent. Binding studies revealed the presence of a single class of high-affinity binding sites with an apparent Kd of 15.3 nM. The number of receptor sites was calculated as 8.48 x 10(5) sites/cell. Mesangial cells exposed to beta-endorphin (10(-6) M) for 48 h showed enhanced incorporation of [3H]thymidine when compared to untreated cells (control, 23,228 +/- 2,778 cpm/well vs. beta-endorphin, 44,887 +/- 4,259 cpm/well; p less than 0.01). Our results show that mesangial cells carry a specific receptor for beta-endorphin which may be linked to proliferation of mesangial cells.
Singhal
P C
PC
Department of Medicine, Long Island Jewish Medical Center, Albert Einstein College of Medicine, New York, N.Y.
Driesbach
A L
AL
Abramovici
M
M
Gibbons
N
N
Goyal
N
N
D000818:Animals; D002455:Cell Division; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D005920:Glomerular Mesangium / Q000737:chemistry* / Q000166:cytology* / Q000648:ultrastructure; D007457:Iodine Radioisotopes; D051381:Rats; D011957:Receptors, Opioid / Q000032:analysis* / Q000378:metabolism; D012984:Software; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors; D014316:Tritium
D007457:Iodine Radioisotopes; D011957:Receptors, Opioid; D014316:Tritium; D004247:DNA; D013936:Thymidine