Effect of verapamil on 45Ca uptake by synaptosomes.
The effect of verapamil on K-stimulated 45Ca uptake (the difference between uptake in 60 mM-Ko medium and 5 mM-Ko medium) was studied using a synaptosomal fraction from rat brain. Verapamil inhibited K-stimulated 45Ca uptake, but not 45Ca uptake in 5 mM-Ko media (1 mM- and 0.1 mM-Cao media). The concentrations of verapamil inducing 50% inhibition of K-stimulated 45Ca uptake (ID50) in 1 mM- and 0.1 mM-Cao media were not significantly different, being about 10(-4) M and 2 X 10(-4) M, respectively. Like verapamil, Mn++ inhibited only K-stimulated 45Ca uptake, but its ID50 values in 1 mM- and 0.1 mM-Cao media were about 1.7 mM and 0.2 mM, respectively. It is considered from these findings that both verapamil and Mn++ specifically inhibit K-stimulated 45Ca uptake, but the modalities of their inhibitory effects on K-stimulated 45Ca uptake are different.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003864:Depression, Chemical; D066298:In Vitro Techniques; D008297:Male; D008345:Manganese / Q000502:physiology; D011188:Potassium / Q000502:physiology; D051381:Rats; D013574:Synaptosomes / Q000378:metabolism*; D013997:Time Factors; D014700:Verapamil / Q000494:pharmacology*
D008345:Manganese; D014700:Verapamil; D011188:Potassium; D002118:Calcium