Influence of long-term treatment with the Ca2(+)-antagonists nifedipine, verapamil, flunarizine and with the calmodulin antagonist trifluoperazine on beta-adrenoceptors in rat cerebral cortex.

1. The binding of [3H] dihydroalprenolol ((3H]DHA) to beta-adrenoceptors in cerebral cortex membranes (fraction P2) was studied after 13-day oral treatment of male Wistar rats with the Ca2(+)-antagonists nifedipine (20 mg/kg), verapamil (50 mg/kg), flunarizine (10 mg/kg) and with the calmodulin (CaM)-antagonist trifluoperazine (TFP) (3 mg/kg). 2. A significant reduction in the number (Bmax) of binding sites for [3H]DHA was established after the 3 Ca2(+)-antagonists as well as after TFP. 3. No changes in the affinity values (Kd) [3H]DHA binding were found in all treated groups. 4. The fluidity characteristics of the cerebral cortex membranes in nifedipine- and flunarizine-treated rats did not differ from those in controls. 5. Based on these results, we concluded that long-term treatment with Ca2(+)- and calmodulin-antagonists might induce changes in the central adrenergic mechanisms.