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Baroreceptor reflex control of heart rate in rats studied by induced and autogenic changes in arterial pressure

Departments of ¹Psychology and ²Pharmacology, and the ³Cardiovascular Center, University of Iowa, Iowa City, Iowa

Submitted 23 January 2004 ; accepted in final form 30 December 2004

The function of the arterial baroreflex has traditionally been assessed by measurement of reflex changes in heart rate (HR) or sympathetic nerve activity resulting from experimenter-induced manipulation of arterial blood pressure (the Oxford method, also termed the pharmacological method). However, logistical and flexibility limitations of this technique have promoted the development of new methods for assessing baroreflex function such as the evaluation of changes in spontaneous arterial pressure and HR. Although this new spontaneous method has been validated in dogs and humans, it has not been rigorously tested in rats. In the present study, the method of correlating spontaneous changes in systolic blood pressure and HR was evaluated in resting, normotensive Sprague-Dawley rats. This technique was found to be neither reliable nor valid under the conditions employed in the present protocol. We also tested a variation of the spontaneous method that evaluates particular sequences of data during which arterial pressure and pulse interval are changing in the same direction for at least three consecutive heartbeats (the sequence method). The sequence method did not provide extra reliability or validity over the spontaneous method. We conclude that due to the restricted range of variability obtained by measuring spontaneous blood pressure fluctuations, the spontaneous and sequence techniques do not provide data that are comparable to the traditional method of assessing HR changes triggered by arterial blood pressure increases and decreases induced by vasoactive drugs. However, it is possible that surgical stress obscured the relationship between blood pressure and HR, and therefore additional studies are needed to determine whether the spontaneous and sequence methods can be applied to rats during different behavioral states.

atropine; phenylephrine; propranolol; reproducibility of results; sodium nitroprusside; validity

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Corrigendum

AJP - Heart 2006 291: H1488. [Full Text]  

This article has been cited by other articles:

				H. M. Stauss, J. A. Moffitt, M. W. Chapleau, F. M. Abboud, and A. K. Johnson Baroreceptor Reflex Sensitivity Estimated by the Sequence Technique is Reliable in Rats Am J Physiol Heart Circ Physiol, July 1, 2006; 291(1): H482 - H483. [Abstract] [Full Text] [PDF]