ScienceAsia 16 (1990): 177-185 |doi: 10.2306/scienceasia1513-1874.1990.16.177

COLLAGENASE DIMINSHES MUSCARINIC RECEPTOR BINDING IN PARTIALLY PURIFIED BOVINE ADRENAL CHROMAFFIN CELLS

BANTHIT CHETSAWANG,^a NAIPHINICH KOTCHABHAKDI,^a CHAINARONG CHERDCHU^b AND PIYARAT GOVITRAPONG^a

ABSTRACT: The presence of muscarinic receptors in partially purified intact bovine chromaffin cells was investigated by binding assay using the antagonistic-specific high affinity ligand, [³H] -quinuclidinyl benzilate [³H)-ONB]. The kinedcs of [³H]-ONB binding to mechanically isolated intact bovine chromaffin cells was examined. The specific [³H]-ONB binding to mechanically isolated intact bovine chromaffin cells that were treated with 0.1 % or higher collagenase concentrations was decreased. Scatchard analysis combined with computer program "LIGAND" was used for characterization of the specific [³H]-ONB binding. It was found that partially purified, mechanically and enzymaticaIly (0.15% caIIagenase) isolated bovine chromaffin cells each had a single high affinity class of binding sites with a Kd of 0.12 O.02 nM and 0.14 O.06 nM and a B_max of 3.1 0.6 fmol/10³ cells and 0.021 0.0007 fmol/10³ cells, respectively. These data demonstrated that 0.15% coIIagenase treatment decreases the receptor density (Bma) of muscarinic receptors in partiaIIy purified bovine chromaffin cells while the K_d remains unchanged

Download PDF

a Neurobehavioural Biology Center, Mahidol University, SaIaya Campus, Nakompathom 7317, Thailand.
b Department of Pharmacology, Pramongkutklao College of Medidne, Bangkok 10400, Thailand.

Received 12 December 1990