Specific binding of nerve growth factor to normal and denervated canine heart

Preparations of membranes from normal and surgically denervated canine heart were tested for binding of radiolabeled nerve growth factor. Specific binding was detected in both normal and denervated hearts. Binding was nonsaturable and complex for normal atria and ventricles and denervated atria but appeared to be saturable for denervated ventricles. Nerve growth factor bound per microgram of protein was lower in denervated ventricles than normal ventricles, whereas slightly higher binding to denervated atria than normal atria was observed. This binding could not be displaced by cytochrome c, insulin, or epidermal growth factor. The data indicate that a large part of binding to normal ventricles could be due to nerve terminals attached to the heart, but specific binding detected in the denervated ventricles may be an intrinsic property of the tissue itself. These sites may serve as storage or uptake sites to direct sympathetic innervation in the developing or reinnervating myocardium.