Hormonal regulation of membrane calcium channels in the heart

: It has been shown on the trabecules of frog auricle by potential recording, that prostaglandin E1 (PGE1) increases the number of working calcium channels of the membrane. PGE1, PGE2, acetylcholine, indometacin--inhibitor of PG synthesis and aminazine 2--calmodulin inhibitor do not decrease novodrin--induced intensification of calcium current. The results suggest that a change of cAMP level inside the cell modulates the number of working calcium channels. PG and calmodulin are not necessary for novodrin--stimulation of adenylatcyclase (AC). The effect of acetylcholine is not connected with AC inhibition.