Effects of nonspecific smooth muscle relaxants on tissue concentrations of high energy phosphates and mechanical activity of normal polarized and depolarized intestinal smooth muscles from guinea pig.

Effects of nonspecific smooth muscle relaxants, an uncoupler and removal of Ca ions from physiological solution on the tissue concentrations of high energy phosphates, such as ATP and creatine phosphate (CP) and tension of the normal polarized and KCl-depolarized intestinal smooth muscles of guinea pig were studied. Decrease of CP-concentration induced by dinitrophenol (DNP; 10(-4) M) was accompanied by relaxation of the normal polarized and KCl-depolarized smooth muscles. DNP slightly (but significantly) decreased ATP-concentration in the normal polarized and KCl-depolarized smooth muscles. Application of papaverine ( 3 x 10(-5) M) relaxed the normal polarized taenia immediately but increased CP-concentration at 5 and 10 min and decreased the concentration at 20 min. When the depolarized smooth muscle was considerably relaxed by papaverine (3 x 10(10-5) M), there was little influence on the CP-concentration. After relaxation of the depolarized taenia as induced by papaverine had reached a maximal amplitude, CP-concentration decreased significantly. ATP-concentration was little influenced by papaverine in the normal polarized and KCl-depolarized muscles. Although the treatments with a synthetic antispasmodic drug, Aspaminol (3 x 10(-4) M), which was found to inhibit Ca-uptake by the intestinal smooth muscles, a Ca-blocker, D-600 (10(-6) M) and removal of Ca ions from physiological solution relaxed the polarized and depolarized smooth muscles, the tissue concentrations of CP and ATP increased. These phenomena are considered to be due to decrease of the intracellular Ca-concentration.