Possible Interaction: Gamma-Aminobutyric Acid and Verapamil

“Pharmacological activation of L-type voltage-operated calcium channels with BayK 8644 produced a decrease in [cAMP]i similar to that induced by GABA, while blocking these calcium channels with verapamil reversed the effect of GABA on cAMP synthesis.”

“ Verapamil can inhibit fertilization in vitro through regulating Myb expression of sperm, while GABA , dbcAMP and Verapamil may affect the process of fertilization through the way other than Myb expression.”

“The [Ca(2+)](i) rise due to GABA was suppressed in the absence of extracellular Ca(2+) or in the presence of the L-type voltage-gated Ca(2+) channel blocker, verapamil , suggesting that Ca(2+) may be entered through L-type Ca(2+) channels.”

“Diltiazem, verapamil and methoxyverapamil (D 600) inhibited K+-evoked (30 mM) GABA release at very high concentrations (> 1 μM).”

“The voltage-dependent Ca2+ entry due to K+ depolarization, after maximal Ca2+ loading of the synaptosomes by Na+/Ca2+ exchange, and the consequent [3H]GABA release could be blocked by 50 μM verapamil.”

“On the basis of these results we conclude that amiloride and verapamil inhibit high K+-induced release of [3H]GABA by antagonizing the entrance of Ca2+ (and possibly Na+ when external Ca2+ is absent) through a population of voltage sensitive presynaptic Ca2+ channels activated by depolarization.”

“It is concluded that in addition … the Ca2+ antagonistic properties of verapamil on the Ca2+‐dependent, depolarization‐… release of some neurotransmitters [ gamma aminobutyric acid (GABA and NE)], another mechanism probably mediated by presynaptic receptors underlies the effects of verapamil on DA and 5‐HT release from discrete brain regions.”

“The ability of progesterone, GABA , or muscimol to stimulate exocytosis was blocked by the Ca2+ channel antagonists verapamil or nifedipine.”

“In addition, GABA evoked an increase in [Ca2+]n measured by indo-1 fluorometry, which was depressed in the presence of verapamil or picrotoxin.”

“The GABA or muscimol effect on [Ca2+]i was antagonized by nifedipine (10 microM) or verapamil (50 microM), and completely abolished in the presence of 4 mM EGTA (low-calcium medium).”