Receptor Determination DHP Binding Sites on Surface Membranes

2 Receptor Determination DHP Binding Sites on Surface Membranes 

Surface membranes of excitable cells contain a voltage-dependent L-type calcium channel, a membrane-spanning complex of several proteins. This complex is a valuable marker for this membrane type. It binds very specific calcium channel antagonists, such as, for instance, drugs of the dihydropyridine (DHP) type as (-i-)-PN 200-110 or nitrendipine. 

Important DHP s are light sensitive. Avoid daylight and work in a dark room illuminated by yellow light (e.g., sodium light source). 

50 mM Tris, pH 7.4, 2 mM CaCh, 0.1 mM PMSF (added just before use) 

Dilute a membrane preparation to about 0.4 mg protein per milliter or cell suspensions to about 10 cells/ml with Soln. A. Prepare four 1 3 dilution series of Soln. B using Soln. A as diluent (dilutions 0 to 4 ). Pipet 50 pi of dilutions 0 to 4 as duplicates into scintillation vials to define the total radioactivity values Totalo to Total4.  

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S.3.2.2 Receptor Determination DHP Binding Sites on Surface Membranes... 

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