To evaluate utilization of added calcium chloride, calcium chloride-induced initial recovery and late recovery responses in isolated mouse duodenum were observed in the presence of calcium channel antagonists. Depressed tension of
isolated duodenum incubated with calcium-free Throde solution was regained by the addtion of calcium chloride(4mM). The recovery showed two phase. initial sudden recovery followed by late sustained recovery Initial recovery by
calcium
chloride addition to calcium-free solution was not affected by the presence of diltiazem (3.3×10-4 and 6.6×104 mM), and the late recovery was tend to be depressed. In calcium-potassium-free solution, the initial recovery was not affected,
however, late recovery was markedly depressed.
The initial recovery in calcium-free, and calcium-potassium-free solution was little affected by the presence of nifedipine(4.3×10-5 and 8.6×105mM), while the late recovery was more depressed n calcium-free solution than in
calcium-potassium-free solution.
The initial recovery in calcium-free solution was little affected by the presence of verapamil(1.2×104 and 2.9×10-4mM), but the late recovery was depressed. however, the initial recovery in calcium-potassium free solution was
depressed
by verapamil at 1.2×104mM, but not at 2.9×104mM.
These results indicate that calcium-channel antagonists inhibit late recovery phase rather than initial recovery phase induced by addition of calcium chloride regardless to the presence of physiologic concentration of potassium ions in
calcium
free
solution.
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