The actions of D 600, aspaminol and papaverine on calcium-, potassium- and histamine-induced contractions of isolated rabbit basilar artery, aorta, taenia coli and tracheal smooth muscle.

The effects of D 600, Aspaminol (1,1-diphenyl-3-piperidinobutanol hydrochloride) and papaverine on CaCl2-, KCl- and histamine-induced contractile responses of isolated rabbit basilar artery, aorta, taenia coli and tracheal smooth muscle were compared with each other. D 600 reduced CaCl2-induced maximal responses in basilar artery and aorta, and parallelly shifted the concentration-response curves for CaCl2 to the right in taenia coli and trachea. D 600 also reduced histamine-induced maximal contractions in basilar artery and taenia coli. These reductions were not reversed by increasing CaCl2 concentration in bathing fluids. High concentration of D 600 parallelly shifted the concentration-response curve for histamine to the right in aorta. Like D 600, Aspaminol, a nonspecific smooth muscle relaxant, parallelly shifted the concentration-response curve for histamine in aorta. Papaverine parallelly shifted the concentration-response curve for CaCl2 in taenia coli and reduced the maximal responses in other tissues. Papaverine also reduced histamine-induced maximal responses in basilar artery, aorta and taenia coli. Influences of these smooth muscle relaxants on histamine-induced contraction in Ca-free buffer solution and on KCl-induced contraction in normal and high Ca (Ca: 12.5 mM) buffer solution were also studied. From the results obtained in this study, the effects of smooth muscle relaxants are considered to vary with the type of smooth muscle or the condition eliciting contraction, and the possible mechanisms of the contractions were discussed.