Author: Toska, K.

Source: Acta Physiologica, Volume 200, Number 3, November 2010 , pp. 211-221(11)

Publisher: Wiley-Blackwell

Abstract:

Aim: 

The hypothesis that isometric handgrip induces a progressive increase in arterial pressure and a linear increase in setpoint for arterial pressure control was tested. Methods: 

The continuous time course of changes in heart rate (HR), stroke volume (SV) and mean arterial pressure (MAP) was recorded during a 2-min handgrip contraction of 40% of maximal voluntary contraction force. Twice during the development of the handgrip-induced, gradual pressure increase of ∼25 mmHg, additional, transient changes in arterial pressure were mechanically induced. The subsequent baroreflex responses to these additional pressure changes were studied. The additional steep increase in arterial pressure (∼10 mmHg) was induced both after 70 and 100 s of handgrip contraction, by inflating bilateral thigh cuffs to suprasystolic pressure. Cuff pressure was released after 10 s, thus introducing a steep decrease in MAP. Results: 

During the development of the handgrip-induced pressure increase, HR increased, SV decreased, cardiac output (CO) increased slightly and total peripheral conductance (TPC = CO/MAP) increased (i.e. peripheral vasoconstriction). The circulatory responses to the additional, sudden increase and subsequent decrease in arterial pressure after 70 and 100 s perfectly adjusted arterial pressure back to the linear increase in MAP, indicating an effective baroreflex response. Conclusion: 

The increase in MAP which characterizes handgrip-induced pressure response can be regarded as a result of a gradual increase in the set point of the arterial baroreflexes, with no change in the time course and magnitude of the baroreflex responses to additional, induced changes in MAP.

Keywords: baroreflex; blood pressure regulation; heart rate; human cardiovascular control; peripheral conductance; stroke volume

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1748-1716.2010.02144.x

Publication date: 2010-11-01

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