Low-frequency blood pressure oscillations in mesenteric vessels in conscious rats

Systemic arterial pressure is determined by a complex interaction between t he general control of the circulation and locally acting mechanisms which s erve the local demands of the vascular region. The general control can be s tudied by measuring fluctuations in the systemic mean arterial blood pressu re (sysMAP) and cardiac output. Specific mechanisms, characterizing a given vascular region, can be studied by measuring local blood pressure simultan eously with sysMAP, By comparing these two signals the activity of local me chanisms can be elucidated. The present work was aimed at studying the char acteristics of tone regulation in the mesenteric vascular bed. Recently, a new technique was developed for recording the mean intravascular pressure a t the base of the mesenteric arcade (mesMAP; at the point where the arcade runs closest to the intestinal wall) in conscious, unrestrained rats [1, 2] , This technique showed that, in the rat mesenteric vascular bed, arteries proximal to the mesenteric arcade (with diameter of >200 mu m) contribute s ubstantially to the control of peripheral resistance, In the present study we applied this approach for the investigation of short-term blood pressure variability. This allowed us to observe regular oscillations of mesenteric vascular tone, probably resulting from vasomotion-like vessel activity.