Possible Interaction: Quinidine and Calcium Supplement

“Using isolation cell procedure and whole cell recording, we found that 10 μM quinidine (34.77±6.5%, n=5) and 0.5 μM flecainide (50.46±6.2%, n=4) decrease calcium current in human atrium.”

“Oligomycin (10 micrograms/ml) and quinidine (1 mM) inhibit the rate of Ca uptake by inhibiting Ca-induced changes in the K permeability.”

“It is concluded that quinidine reduces the membrane conductances for sodium, calcium , and potassium ions.”

“ Quinidine inhibition is only slightly lessened by Ca+2 so that it appears that the site of action of quinidine may not involve a Ca+2 ion stabilizer.”

“ Quinidine caused a transient increase in free internal calcium but decreased calcium after a 48 h incubation period.”

“The activity of the high-conductance, Ca2+ -activated, voltage-dependent K+ (BKCa) channel, which is primarily responsible for basolateral K+ recycling during Na+ absorption, was inhibited by 10–30 μM quinidine or propafenone in the form of a rapidly dissociating block.”

“ Quinidine (>0.5 mmol/l) decreased the Ca2+ uptake (soleus>adductor magnus>papillary muscle) and increased the Ca2+ release [papillary muscle=soleus ≫ adductor magnus (only at 1.5 mmol/l, the highest concentration tested)] from the SR of all three muscles in a dose-dependent manner.”

“ Quinidine , 10 μm, decreased the amplitude of the voltage‐dependent Ca current to only a small extent (15% decrease at 0 mV).”

“ Quinidine reversibly decreased peak calcium current as well as the slowly inactivating and/or steady-state inward currents in the plateau voltage range, presumably both "late" sodium (tetrodotoxin-sensitive) and calcium (tetrodotoxin-insensitive) currents.”

“Both the transient and the sustained hyperpolarization evoked in smooth muscle cells in the presence of procainamide (15 min) or quinidine in calcium-containing or in calcium-free solution, respectively, were inhibited.”