Long term objective is to develop pressure transducer preparations for chronic implantation in rats & mice. Specific aims: develop a 1.3 mm dia implantable transducer for rats; implantable mating dome/cannula/flushing system for mice; & accessory electronics for interfacing with monitoring systems. Rats & mice are replacing larger mammals in cardiac research for budgetary & societal reasons. No suitable chronic implantable pressure preparations are now available. Implantable transducers have been shown to substantially reduce mortality & morbidity in experimental animals, permitting longer surveillance time, better quality data. Methodology for achieving goals: design/procure .23 x .30 mm strain gages; design/fabricate 1.3 mm dia transducers; develop new metal/semiconductor interface to reduce baseline drift. The proposed 1.3 mm implantable prototype transducer can be produced in Phase I. Success will justify feasibility of Phase II goals: economic production design; implantable low compliance dome/cannula systems for mice; support electronics. Experience with larger-sized implantable transducers has shown extension of such technology to innovative configurations in other species/organs applications.