Abstract
Specific binding of tritiated quinuclidinyl benzilate (3H-QNB) to surface membrane muscarinic receptors was utilized to identify plasma membrane (PM) fractions from smooth muscle of the rabbit urinary bladder. Accumulation of3H-QNB in the PM fraction was 4–5-fold higher than that in fractions of endoplasmic reticulum (EM) or mitochondria (M). A similar pattern of