Possible Interaction: Manganese and Verapamil

“Both nickel and verapamil produced a non-significant decrease in Mn and Ca influx.”

“It is concluded from the study that 50 μmol of manganese, although effective in tissue protection, cannot substitute totally for the loss of calcium during calcium-free perfusion and that manganese may substitute for the micromolar calcium needed for tissue protection by verapamil.”

“The presence of verapamil prior to (5 min), during (5 min) and following (5 min) calcium-free perfusion combined with the presence of manganese conferred a further protection, particularly in the total paradox.”

“In cells depolarized with KCl (45 mM), enhanced manganese uptake or increased cytosolic calcium were inhibited with verapamil (10 microM).”

“Reduction of extracellular Ca2+ concentration from 1.25 mM to 0.25 mM or the use of 1 microM verapamil and 2 mM manganese increases the relative potentiation of post-rest contractions.”

“Calcium may be continuously supplied to these stores from the extracellular space in the presence of verapamil through a pathway that is inhibited by manganese.”

“The stimulatory effect of verapamil in calcium-free solution and the restoration of the effect by the calcium readmission were both blocked by pretreatment with manganese ions.”

“Reagents which have been shown to affect the Ca channel of isolated … muscle using a voltageclamp technique, also affect similarly the rate of Mn uptake by … rat heart: Verapamil (2 μ m ) inhibited Mn uptake 73%, oligomycin (2 μ m ) inhibited 55% and isoproterenol (2 μ m ) stimulated 80%.”

“… verapamil … manganese are both known to interfere with excitation-contraction coupling of smooth muscle, perhaps by inhibiting transcellular calcium transport, the present results suggest that the … an important cofactor required for the expression of AII action on the glomerular microcirculation, by affecting mesangial and efferent arteriolar smooth muscle contractility.”