Effects of Ca-antagonists and antispasmodic drugs on contraction by ACh in molluscan smooth muscle.

The influence of Ca-antagonists and antispasmodic drugs on contractions by ACh and by DMPP were investigated. Verapamil (10(-5) to 10(-4) M), diltiazem (10(-5) to 10(-4) M) and D-600 (10(-5) to 10(-4) M) depressed both the contractions in a dose dependent manner. Papaverine (10(-5) to 10(-4) M) and Aspaminol (10(-6) to 10(-5) M) also depressed both the contractions in a dose dependent manner. These findings indicate that Ca2+, which initiates the contraction by ACh, is supplied from both the external medium and intracellular store sites.