A ventricular pressure-clamping system for the study of mechano-electrical feedback.

It is necessary to control the mechanical stimuli precisely in the studies of cardiac mechano-electrical feedback (MEF). In the present study a ventricular pressure-clamping system has been developed, which can be applied to isolated-perfused rabbit hearts. Controlled by a computer, this system not only can make the left ventricle follow a command defining the same pressure wave as that during a beating cycle under physiological condition, but also deliver mechanical stimuli with a proper waveform to the ventricle at a particular time phase. This system integrates multiple functions, including perfusing, pacing, recording of electrocardiogram and monophasic action potentials, and clamping and measuring of ventricular pressures in isolated-perfused hearts. Thus, it is a distinct system for investigating the phenomena and mechanisms of cardiac MEF at organ level.

[Improved methods for researching isolated carotid sinus baroreceptors automatically controlling for sinus pressure].

OBJECTIVE: To develop a system for automatically controlling carotid sinus pressure in the study on baroreceptors. METHODS: The preparation containing carotid sinus with parts of the connected vessels and carotid sinus nerve (CS-CSN) were isolated and perfused. A critical pressure controlling component (PRE-U, Hoerbiger, Deutschland) dictated by a computer was integrated into the system to clamp the intrasinus pressure. The pressure command and the relevant intrasinus pressure were compared to evaluate the validity of the pressure controlling system. RESULTS: A variety of sinus pressure-controlling patterns, including pulsation, ramp and step pressures, could be achieved accurately by using the system, and the pressure-dependent discharge activities of sinus nerve were confirmed. CONCLUSION: This system for clamping carotid sinus pressure could realize multiple pressure-controlling patterns and is a useful and flexible pressure controlling method that could applied in the study on mechano-electric transduction of baroreceptors.