THE EFFECTS OF CAFFEINE AND IMIDAZOLE ON THE ACTIONS OF BETA- AND ALPHA-ADRENERGIC STIMULANTS, PAPAVERINE AND CYCLIC 3', 5'-AMP

Abstract

In previous papers (1, 2) we have reported, using the taenia of the guinea pig, that isoprenaline, papaverine and dibutyryl cyclic AMP stop the spontaneous spike discharge with some hyperpolarization, when these relax the taenia, also that these drugs are without any effect on tension of the glycerinated taenia induced by ATP and Ca in sufficient concentrations to relax the taenia. Furthermore, we have observed that all of three drugs accelerate Ca-efflux in the taenia (3). These results suggest that the inhibitory actions of these three drugs may be mediated through one mechanism, though only isoprenaline induces the inhibitory response via the β-adrenergic receptors.