A SIMPLIFIED PAIRED NECK CHAMBER FOR THE DEMONSTRATION OF BAROREFLEX BLOOD PRESSURE REGULATION

I n this investigation a simplified variable-pressure paired neck chamber was developed as a practical alternative to traditional neck collar designs used to study the arterial baroreceptor reflex in humans. The purpose of this new design was to extend the use of the noninvasive neck chamber method of baroreceptor investigation to teachers of physiology. Performance tests indicate that these new chambers are capable of delineating the stimulus-response relationship for both the blood pressure baroreflex [sensitivity ϭ 0.425 Ϯ 0.13 mmHg mean arterial pressure (MAP)/mmHg neck chamber pressure (NCP); range ϭ 24.9 Ϯ 4.6 mmHg MAP] and the heart rate baroreflex (sensitivity ϭ 0.273 Ϯ 0.12 beats . min Ϫ1. mmHg NCP Ϫ1 ; range ϭ 16.7 Ϯ 6.8 beats/min). This was achieved by applying localized positive and negative air pressures to the carotid sinuses throughout the range from ϩ60 to Ϫ60 mmHg in steps of 20 mmHg. This simplified neck chamber method offers distinct methodological advantages over traditional neck collars, making it a valuable tool for demonstrating baroreflex regulation of the circulation. S60-S66, 1999. Key words: carotid baroreceptors; cardiovascular; neck suction Experimental techniques in physiology often are not accessible for the purpose of teaching unless the institution conducts specialized research in a given field. This problem can be further complicated by the lack of availability of noninvasive methods that are preferable for the demonstration of key physiological mechanisms in a learning environment. The study of baroreflex blood pressure control is one such mechanism that provides students with a valuable insight into regulation of the circulation. This is also an example, however, of a case in which practiced research methods have not made the transition into the teaching laboratory, and that is the problem addressed here. AM. J. PHYSIOL. 277 (ADV. PHYSIOL. EDUC. 22): Study of the carotid baroreflex was greatly expanded after the original development of the noninvasive variable-pressure neck chamber method (9). Because of the accessibility of the carotid sinus, with the use of this approach the carotid baroreceptor afferent nerve activity may be manipulated directly, which was not previously possible in human volunteers. The blood pressure, heart rate, and vascular responses to altered baroreceptor input can then be studied to gain important information concerning autonomic regulation of the circulation. Since its inception over 40 years ago, however, during which time there have been several advances to the original neck chamber I N N O V A T I O N S A N D I D E A