In rat lacrimal glands, Forskolin induces a dose-dependent [3H]protein release. This effect can be potentiated by papaverine. As for the other inducers whose effects on protein secretion are assumed to be cAMP-mediated, Forskolin secretion time course shows a latency. Isoproterenol decreases the Forskolin EC 5- at least 60--times. On the other hand, Forskolin enhances the efficacy of isoproterenol without affecting its potency. As a whole, the data collected show that isoproterenol-induced [3H]protein secretion in rat lacrimal glands involved adenylate cyclase activation by coupling with β-adrenergic receptors.
