Effects of Papaverine Derivatives on Cyclic 3’, 5’-AMP Phosphodiesterase and Relaxation of Rabbit Ileum
The effects of papaverine derivatives on cyclic 3’, 5’-AMP phosphodiesterase (PDE) and on the spontaneous contractions of isolated rabbit ileum were investigated. There was a strong correlation between the relaxing activity and the inhibition of PDE for eupaverine, ethylpapaverine and papaverine. Eupaverine was the most effective spasmolytic agent and the most potent inhibitor of PDE activity, followed by ethylpapaverine and papaverine. In contrast we found a very strong relaxing effect but only slight inhibition of PDE activity by tetrahydropapaveroline (THP). Decreased contractions could be mimicked by exogenously given cyclic AMP and cyclic dibutyryl AMP. Our results support the assumption that smooth muscle relaxation in rabbit ileum is mediated by cyclic AMP.
KeywordsOrgan Bath Smooth Muscle Relaxation Spontaneous Contraction Neural Transmission Spasmolytic Action
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