The presence of sigma-receptors in the lacrimal gland.
Applying the technic of S.A. Wolfe et al. [Endocrinology, 124, 1160-1172, 1989], we have established the presence of sigma receptors in isolated, but intact, lacrimocytes excised from main lacrimal gland tissue of the New Zealand white rabbit. 3H-Haloperidol was used as the ligand (0.5-2500 nM), in the presence of spiperone. From a Scatchard plot, a single binding site was statistically chosen over two sites for a majority of the data associated with the intact lacrimocytes. Kd (71.0 +/- 46.4 nM) and Bmax (588.2 +/- 166.7 fmol/mg of protein) values showed lower binding affinity but a similar density of sigma sites in rabbit lacrimocytes when compared to published results obtained for rat exocrine glands and brain tissue. Using the technic of McCann and Su [J. Pharm. Exp. Therap., 257, 547, 1991], membrane suspensions of the sigma receptor were also prepared and tested for binding to radioligands, 3H-DTG, as well as 3H-haloperidol. A Scatchard plot revealed two binding sites for 3H-DTG and one binding site for 3H-haloperidol. The high affinity site for 3H-DTG yielded a Kd of 1.04 +/- 0.64 nM, whereas, Bmax was 135.9 +/- 11.62 fmol/mg of protein. The low affinity site gave a Kd = 75.3 +/- 26.8 nM and Bmax = 344.0 +/- 222.0 fmol/mg of protein. The weaker site is suspected to be intracellular. IC50 values were determined for N,N-disubstituted arylphenylalkylamines (Kd approximately low nM).
Schoenwald
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Division of Pharmaceutics, College of Pharmacy, University of Iowa, Iowa City.
Barfknecht
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Xia
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Newton
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D000818:Animals; D001667:Binding, Competitive; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D005260:Female; D006146:Guanidines / Q000378:metabolism; D006220:Haloperidol / Q000378:metabolism; D007765:Lacrimal Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D011817:Rabbits; D011869:Radioligand Assay; D017480:Receptors, sigma / Q000378:metabolism*; D013134:Spiperone / Q000378:metabolism
D006146:Guanidines; D017480:Receptors, sigma; D013134:Spiperone; D006220:Haloperidol; C050232:1,3-ditolylguanidine