This project continues to be devoted to the improved understanding of reproductive smooth muslce function. The experimental approach has centered on the application of electrophysiological techniques, specifically voltage-clamp techniques. Since the first publication on this approach we, along with others including cardiac physiologists, have become increasingly concerned with the interpretation of voltage-clamp data from multicellular preparations in the double sucrose-gap. This concern provided the impetus for a major effort to evaluate the quality of voltage control. In addition to the theoretical considerations cited above, experimental objectives dealing with the problems of complex tissue geometry have been to: (1) work with smaller multicellular preparations and exploit the simple geometry of the isolated cell system and (2) develop improved and new electronics of the recording system. A further objective has been to broaden our experimental approach to the study of electrical behavior in smooth muscle-- specifically to include the analysis of subthreshold pacemaker electrical events and to consider their functional relationship to the Hodgkin-Huxley-like event of the action potential. BIBLIOGRAPHIC REFERENCES: Anderson, N. C., and F. Ramon. Interaction between pacemaker electrical behavior and action potential mechanism in uterine smooth muscle in: Physiology of Smooth Muscles, Raven Press, ed. E. Bulbring and M.F. Shuba pp 53-63 (1976). Fletcher, W. H., N.C. Anderson and J. W. Everett. Intercellular communication in the rat anterior pituitary gland. J. Cell Biol. 67, 469 (1975).