3H-Nitrendipine binds with high affinity to brain membranes, and its binding sites seem to be part of the voltage-dependent calcium channel complex. In rat caudate nucleus, these (Ca2+ channel complex) are mainly located in intrinsioc neurones; after injection of Kainic acid in caudate nucleus, the number of 3H-nitrendipine binding sites and the veratridine-elicited increase of 45Ca2+ uptake were ablated. After long-term treatment of mice with Nifedipine or Verapamil, the density of 3H-Nitrendipine binding sites was reduced by 40% in caudate nucleus, hippocampus and cerebral cortex. Previous evidence indicates the presence in rat brain of an endogenous ligand that modulates 3H-Nitrendipine binding sites.
