The influence of low and high doses of theophylline on spontaneous motility and cyclic 3',5' AMP content in isolated rat uterus |
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Authors: | P Mitznegg E Schubert F Heim |
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Affiliation: | Department of Pharmacology, University of Erlangen-Nürnberg, Erlangen, Germany |
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Abstract: | It was found in isolated rat uterus that 5 × 10?4 N theophylline inhibited spontaneous contractions which were restituted by increasing extracellular calcium 4-fold. Tissue level of cyclic 3′, 5′ AMP was not affected. On the other hand, 10?2 M theophylline elevated cyclic 3′, 5′ AMP by 170 % for at least 60 minutes. The concomitant inhibition of spontaneous uterine motility could neither be restituted by increasing calcium up to 40-fold nor by washing. It was suggested that cyclic 3′, 5′ AMP was involved in theophylline-induced uterine relaxation when the drug was administrated in high amounts able to inhibit phosphodiesterase. Small doses of theophylline (5 × 10?4 M) were supposed to initiate relaxing effects by a calcium-antagonistic intrinsic activity. |
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