Effects of nonspecific smooth muscle relaxants on glycogen phosphorylase activity in depolarized taenia caecum of guinea pig.

Effects of papaverine, Aspaminol (an antispasmodic drug), D-600, 2, 4-dinitrophenol and Ca ions on glycogen phosphorylase activity in the KCl-depolarized taenia caecum of guinea pig were tested. External Ca ions dose-dependently activated phosphorylase, indicating that Ca ions, which entered the smooth muscle cells, played an important role in the regulation of phosphorylase activity. Aspaminol, D-600 and removal of Ca ions from bath fluid inhibited phosphorylase activity. Since these treatments relaxed the taenia caecum, the decrease of phosphorylase activity after the treatments may be mainly due to the decrease of energy consumption. Papaverine and 2, 4-dinitrophenol induced an activation of phosphorylase which might be for replenishment of energy stores decreased by them.