The purpose of this proposal is to study the interactions of various neurotransmitters and local hormones on the Ca2 ion metabolism on the rabbit urinary bladder detrusor muscle and neck tissue. The techniques employed in this study will utilize in vitro smooth muscle segments in isolated organ baths in which 45Ca will be employed to measure changes in Ca2 ion uptake and efflux as influenced by autonomic agents, prostaglandin and several naturally occurring peptides. Known antagonists to these agents will be employed in an effort to show that they are acting through specific receptor sites to promote changes in Ca2 ion metabolism. In addition to this, studies on the effects of several local hormones such as histamine and PGs will be undertaken on purified subcellular fraction of detrusor muscle in an effort to establish the existance of any intracellular receptor mediated Ca2 ion responses.