A Commercial Dynorphin Product Was Contaminated and Gave Misleading Results
A commercially purchased synthetic dynorphin A-(1-13) raised cytosolic calcium in rat pituitary cells. However, this effect was NOT caused by dynorphin itself. When the same preparation was purified by HPLC, the calcium-raising effect disappeared. HPLC combined with LHRH radioimmunoassay revealed contamination with a LHRH-like compound (luteinizing hormone-releasing hormone). The LHRH antagonist blocked the calcium effect, confirming the contamination. Pure dynorphin A-(1-13), dynorphin A-(2-13), leu-enkephalin, beta-endorphin, morphine, and U50,488H all had zero effect on pituitary calcium. LHRH itself raised calcium by about 50 nM, which was blocked by the LHRH antagonist.
Knepel, W; Schöfl, C; Wesemeyer, G; Götz, D M · In Vitro