MUSCARINIC RECEPTORS BINDING IN RETINAL-PIGMENT EPITHELIUM DURING RATDEVELOPMENT

[H-3]Quinuclidinyl benzylate (H-3-QNB) specific binding of the develop ing rat retinal pigment epithelium (RPE) and neural retina has been ex amined. The binding of H-3-QNB to RPE was saturable and displaced by t he antagonist pirenzepine. Scatchard analysis of H-3-QNB binding showe d two high affinity sites to RPE, with K-B = 2.6 nM and 45 nM. Specifi c H-3-QNB binding membranes from neural retina exhibited a characteris tic developmental profile. RPE showed a high density of H-3-QNB bindin g sites through all developmental periods studied. The major onset of binding sites is at the time of RPE differentiation. Our data open the possibility of muscarinic receptors being involved in differentiation and/or proliferation of RPE.