Warning: file_get_contents(https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=27614226
&cmd=llinks): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 215
Interaction between the muscle metaboreflex and the arterial baroreflex in
control of arterial pressure and skeletal muscle blood flow
#MMPMID27614226
Kaur J
; Alvarez A
; Hanna HW
; Krishnan AC
; Senador D
; Machado TM
; Altamimi YH
; Lovelace AT
; Dombrowski MD
; Spranger MD
; O'Leary DS
Am J Physiol Heart Circ Physiol
2016[Nov]; 311
(5
): H1268-H1276
PMID27614226
show ga
The muscle metaboreflex and arterial baroreflex regulate arterial pressure
through distinct mechanisms. During submaximal exercise muscle metaboreflex
activation (MMA) elicits a pressor response virtually solely by increasing
cardiac output (CO) while baroreceptor unloading increases mean arterial pressure
(MAP) primarily through peripheral vasoconstriction. The interaction between the
two reflexes when activated simultaneously has not been well established. We
activated the muscle metaboreflex in chronically instrumented canines during
dynamic exercise (via graded reductions in hindlimb blood flow; HLBF) followed by
simultaneous baroreceptor unloading (via bilateral carotid occlusion; BCO). We
hypothesized that simultaneous activation of both reflexes would result in an
exacerbated pressor response owing to both an increase in CO and
vasoconstriction. We observed that coactivation of muscle metaboreflex and
arterial baroreflex resulted in additive interaction although the mechanisms for
the pressor response were different. MMA increased MAP via increases in CO, heart
rate (HR), and ventricular contractility whereas baroreflex unloading during MMA
caused further increases in MAP via a large decrease in nonischemic vascular
conductance (NIVC; conductance of all vascular beds except the hindlimb
vasculature), indicating substantial peripheral vasoconstriction. Moreover, there
was significant vasoconstriction within the ischemic muscle itself during
coactivation of the two reflexes but the remaining vasculature vasoconstricted to
a greater extent, thereby redirecting blood flow to the ischemic muscle. We
conclude that baroreceptor unloading during MMA induces preferential peripheral
vasoconstriction to improve blood flow to the ischemic active skeletal muscle.
free
free
free
