Inferences on the Rapid Metabolism of Exogenously applied ATP in isolated Smooth Muscle Preparations using Pharmacological Studies

Abstract

When ATP or adenosine are applied as relaxants to isolated smooth muscle preparations in organ baths despite the presence of large volumes of nutrient solution containing these compounds it has been difficult to ascertain what compounds and what concentrations of compounds are indeed acting on the receptors of the muscle cell surface. For example it is quite possible that applied ATP is rapidly broken down in the extracellular space and that the metabolites themselves may act on muscle receptors in lieu of or in addition to the added substance. The understanding of what happens in this situation may be complicated by the formation of more than one compound, the uptake of metabolites, e.g. adenosine, into the cells and the diffusion of metabolites into the outside medium.