ABSTRACT
This chapter aims to summarize some salient data of studies that emphasize different mechanisms that may contribute to the modulation of the levels of both inositol phosphates and cyclic adenosine monophosphate (cAMP) in rat and guinea pig myometrial preparations. In the intact estrogen-treated guinea pig myometrium, prelabeled with [H]inositol, carbachol and oxytocin were found to cause an enhancement in the generation of inositol phosphate accumulation. The effect of isoproterenol on the generation of inositol phosphates was analyzed with the aim of demonstrating possible cross talk between contractants and relaxants at the level of phospholipase C activation. The relative potencies of carbachol in stimulating the generation of inositol phosphates, with an earlier accumulation of InsP3, parallel its activity in attenuating cAMP. In a number of cell types, elevated cAMP levels were found to be associated with an attenuation of agonist-induced phosphoinositide hydrolysis.
