The potentiation of rat uterine inhibitory responses to noradrenaline by theophylline and nitroglycerine

Abstract

1. Dose response curves for noradrenaline were determined before, during and after pretreatment with a variety of agents. The inhibitory response to noradrenaline on the isolated rat uterus was measured according to its ability to inhibit an acetylcholine induced contraction.2. Theophylline, an agent that inhibits phosphodiesterase and increases cyclic AMP levels in the rat, potentiated the response to noradrenaline.3. Pretreatment with cocaine had no significant effect on the potentiation of the noradrenaline response by theophylline.4. Theophylline potentiated the inhibitory response to nitroglycerine.5. Pretreatment with nitroglycerine also potentiated the inhibitory response to noradrenaline.6. Theophylline appears to produce a potentiation of the inhibitory effect of noradrenaline on the rat uterus by means of a non-specific mechanism.