Effects of nonspecific smooth muscle relaxants and Ca-blocker on Ca-release and Ca-binding in microsomal fractions from rabbit taenia coli.

Effects of nonspecific smooth muscle relaxants, papaverine (10(-4) M) and Aspaminol (1,1-diphenyl-3-piperidinobutanol hydrochloride, 10(-4) M), and Ca-blocker, D-600 (10(-6) M) on Ca-release and Ca-binding in the microsomal fractions of rabbit taenia coli were determined. The doses necessary to relax the K-depolarized taenia coli were determined. The doses necessary to relax the K-depolarized taenia coli maximally were used. Ca-binding in the microsomal fractions was inhibited by Aspaminol and D-600 and increased by papaverine in the concentration used. On the other hand, Ca-release from the Ca-incorporated microsomal fractions was inhibited by papaverine and Aspaminol but was not influenced by D-600. Changes observed in Ca-transfer may be related to relaxation of smooth muscle induced by the test drugs.