Ca-channel blockers and the electrophysiology of synaptic transmission of the guinea-pig olfactory cortex.
Slices of guinea-pig olfactory cortex have been used to compare the potency of various Ca-blockers on the electrophysiology of synaptic transmission. Listed in the order of potency, the divalent cations Cd2+, Ni2+, Mn2+, Co2+, La3+ and Mg2+ depressed synaptic transmission. The organic Ca-blockers, nifedipine or nimodipine or verapamil and diltiazem were ineffective up to 0.01 mmol/l. Verapamil, D600 or diltiazem (0.1-0.3 mmol/l) depressed both synaptic transmission and the sodium-mediated presynaptic action potential. These results reaffirm the idea that 'organic Ca-antagonist' do not block all Ca-channels in brain and the high Cd2+ sensitivity suggests the Ca-channels in post- and presynaptic membranes have dissimilar pharmacological profiles.
D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D005971:Glutamates / Q000494:pharmacology; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009830:Olfactory Bulb / Q000187:drug effects*; D009833:Olfactory Pathways / Q000187:drug effects; D013569:Synapses / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*
D002121:Calcium Channel Blockers; D005971:Glutamates; D002104:Cadmium